A fine Mephisto for wordplay, which is to be expected from Don Manley, where my usual approach is wordplay first, and then check the definition. It also helped in this one that two of the more unusual words are very familiar to me.

Definitions, which are underlined can all be confirmed in Chambers, so I will focus on the worplay in the blog.

Away we go...

Across
1	Destroy Scottish island (no small island) (4)
	SLAY - the island is ISLAY, remove the I(island)
4	Harmony around home associated with a fireplace (8)
	CHIMINEA - CHIME(harmony) surrounding IN(home), then A
9	Bacon that I get cooked for flatmate? (10)
	COHABITANT - anagram of BACON,THAT,I
10	Vehicle reversing by French river stopping short — something scraping (7)
	RACLOIR - CAR reversed, then the river LOIRE missing the last letter
13	Little old dam like this bursting? Caution! (6)
	ANICUT - don't often see a clue where the definition is hidden in the middle of the clue - "little old" means O, now take the O out of CAUTION and form the anagram to get the dam
14	My lord always backing soldiers (6)
	MENEER - EER(always) after MEN(soldiers)
16	Papal licence in the name of God ultimately (6)
	INDULT - IN, then D(Deus, God), ULT(ultimately)
17	Quiet repose making one ready, as before (5)
	PREST - P(quiet), REST(repose)
18	No longer chase after prize money, having got weak (6)
	PURSEW - PURSE(prize money), W(weak)
19	Difficult summer month to bear at one time (6)
	AUGEAN - AUG(August, summer month), EAN(bear)
22	Old-fashioned counsel taken on board by daredevil (5)
	AREDE - hidden in dAREDEvil
25	Vassal set to provide cattle food (6)
	MANGEL - MAN(vassal), GEL(set)
28	Come face to face with old bishop and one new to the faith (6)
	OBVERT - O(old), B(bishop), VERT(short for CONVERT, one new to the faith)
29	Learned man to mistreat half a dozen (6)
	MAULVI - MAUL(mistreat), VI(six, half a dozen)
30	Afterwards girl comes to meaningful agreement (7)
	SYNESIS - SYNE(afterwards), SIS(sister, girl)
31	Dearies apt to get excited get breathless (10)
	DEASPIRATE - anagram of DEARIES,APT
32	Homeless creature? Everyone needs to have food, Young Conservative admitted (8)
	ALLEYCAT - ALL(everyone), EAT(have food) containing YC(Young Conservative)
33	Letters from fourth man circulating (4)
	ETHS - the fourth man in the Bible is SETH - cycle it to start at the E

Down
1	Tortures pastors conjured up, having caught highway thief (10)
	STRAPPADOS - anagram of PASTORS containing PAD(short for FOOTPAD, highway thief). Had to laugh at this one, since I am currently playing Falstaff in a production of Henry IV (part the first) and one of the lines in the tavern scenes is "Zounds, an I were at the strappado or all the racks in the world..."
2	Solitary person outside a public library, say? (6)
	LOANER - LONER(solitry person) surrounding A
3	Summon old expert to squash common fellow (6)
	ACCITE - ACE(expert) surrounding CIT(common fellow)
4	Blackmail coming from China not acceptable (5)
	CHOUT - CH(China), OUT(not acceptable)
5	Islander, one wearing headgear — a Scotsman? (7)
	HAITIAN - I(one) inside HAT(headgear) then IAN(Scotsman)
6	Opinion being heard, proceeded secretly (5)
	MINED - sounds like MIND(opinion)
7	Centres in which one sees any number slave, cruelly exploited (6)
	NAVELS - N(any number), then an anagram of SLAVE
8	Friendly agreement? Not with one of two knights opinionated (6)
	ENTETE - the agreement is an ENTENTE, remove one of the N's(knight)
11	Bishop is coming in ruined, upset, in knots (6)
	KNURRS - RR(bishop) inside SUNK(ruined) reversed
12	Embroiderers in Cheshire town registers (10)
	CREWELISTS - the town of CREWE, then LISTS(registers)
15	Internet facility providing e-tunes possibly? (6)
	USENET - anagram of E-TUNES. An internet service of bulletin boards. Anyone still around from the days of rec.puzzles.crosswords?
18	Tree in China at foot of which is girl (7)
	PALMYRA - PAL(China, mate), and MYRA(girl)
20	Cart heading off to deliver piece of armour (6)
	UMBREL - the cart is a TUMBREL, remove the first letter
21	Crocodile gets through biting into girl (6)
	GAVIAL - VIA(through) inside GAL(girl)
23	Net for fish gets some quite sleepy going upstream (6)
	EELSET - hidden reversed in quiTE SLEEpy
24	I’m stupid, restricting power and seeking peace (6)
	DOVISH - Homer Simpson's favorite expression D'OH(I'm stupid) containing VIS(power)
26	Like wine that’s dull from US but with hidden power (5)
	GRAPY - GRAY(dull) containing P(power)
27	Prohibition slapped on revolutionary army in part of Hungary (5)
	BANAT - BAN(prohibition) then a reversal of TA(army)

10:30. Another excellent puzzle from Bob, which I didn’t find particularly hard but nonetheless managed to stuff up, paying insufficient attention to the wordplay at 13ac and bunging in the wrong vehicle. Drat.

Loads of neat stuff in here: the clever device at 2dn is particularly, well, clever.

Definitions are underlined, anagrams indicated like (THIS)*, anagram indicators like this.

Across
1	Takes back fruit unopened (2-7)
	RE-ENGAGES - gREENGAGES. To take back in the sense of re-employing someone, I think.
6	Remains of old underwear
	STAYS - DD. ‘Corsets with bones in them’ (Collins).
9	How you write this answer in wins medals
	VICTORIA CROSSES - VICTORI(ACROSS)ES. Very neat!
10	Drink in small local
	SHANDY - S, HANDY.
11	Inevitably do without mass and church
	PERFORCE - PERFORm, CE.
13	Drag grand star back to an unoccupied carriage
	LUGGAGE VAN - not a term I remember coming across before, so I bunged in LUGGAGE CAR without hesitation. If I had paid the slightest attention to the wordplay I'd have realised that CEGA is not the name of a star, whereas VEGA is. Reverse that, add it to LUG, G (grand) at the beginning and AN at the end and you get the right answer. 'Unoccupied' looks misleadingly like a wordplay instruction.
14	Police unit following a tart
	ACID - A, CID.
16	I popped into friend’s for a beer
	PILS - I ‘popped in’ to PALS to replace the A.
17	He attends an opening ceremony, with one who retains the gold
	DOORKEEPER - DO (ceremony), OR KEEPER. Nicely disguised definition: lift and separate! OR is a heraldry term.
19	A US city concealing an Athenian element
	ANTIMONY - A, N(TIMON)Y. You don’t have to be a Shakespeare expert to know about Timon of Athens.
20	Fight to block the French tariffs
	LEVIES - LE(VIE)S. As Donald Trump is discovering, tariffs are a tax on your own consumers and about as effective a way of getting what you want as punching yourself in the face.
23	Totally innocent, listen as each law is broken
	CLEAN AS A WHISTLE - (LISTEN AS EACH LAW)*.
24	Afterthought added to artist’s files
	RASPS - RA’S, PS.
25	Detectives indict or acquit
	DISCHARGE - DIS, CHARGE.

Down
1	Fumes on board endanger a vessel
	RAVES - contained in ‘endanger a vessel’.
2	How to make Mo and Damon correspond
	EXCHANGE LETTERS - if you exchange the letters in MO AND you get DAMON. Clever!
3	Large number turn to rum and ale unfortunately
	GOOD DEAL - GO, ODD, (ALE)*.
4	Carriage crowd in conversation
	GAIT - sounds like ‘gate’, the crowd at a concert, football match etc.
5	Cabinet has covert broadcast cut short
	SECRETAIRE - SECRET, AIREd.
6	I’m sorry about fatuous, hollow pranks
	SPOOFS - reversal (about) of OOPS (I'm sorry), FatuouS.
7	Pollock, perhaps digest rope securing a boat
	ABSTRACT PAINTER - ABSTRACT (digest), PAINTER. A PAINTER is ‘a line attached to the bow of a boat for tying it up’ and a very useful word for crossword setters. See also ‘sheet’. The one word for a rope that never seems to be used by sailors is ‘rope’.
8	Hose attachment’s main sales feature in poster
	SUSPENDER - S(USP)ENDER. USP stands for ‘unique selling point’.
12	Disco genre newly appreciated
	RECOGNISED - (DISCO GENRE)*.
13	Record about a reindeer, one barely performs
	LAP DANCER - L(A)P, DANCER.
15	Frantic swimmers lapping incessantly
	FEVERISH - F(EVER)ISH. ‘Laps’ in a swimming pool are what North Americans call ‘lengths’.
18	Makes changes to what happens at noon
	AMENDS - AM ends and PM begins.
21	Hide from kids influenced to be outspoken
	SUEDE - sounds like ‘swayed’.
22	Cries to axe top Members of Parliament
	OWLS - hOWLS. ‘Parliament’ being the collective noun for owls, of course.