A straightforward enough solve which I marred with a precipitate entry to 12 down, so my time of 15.38 is moot. I had to guess the blouse at 25, though the wordplay was more than kind, and resist the temptation for a slur on an entire nation at 28. The presence of no less than three words for slow (to the point of stillness) lent a rather languid air o the puzzle, though couple of more lively musical answers picked up the pace. Arguably, there is an unusual split definition at 10. My favourite clue wasthe advice to the police (it made me smile).
My standard clue, definition and SOLUTION conventions are observed[My reasoning]
1 Like bird of old on fruit tree (8)
PLUMAGED Old is AGED and the fruit tree whereon it sits is PLUM. The adjective looks odd until you preface it with some qualifier: brightly plumaged and such.
6 This writer's rubbish is somewhat wicked (6)
IMPISH More often an expression of impatience, especially with tush, PISH is as also a verb meaning pooh-pooh, hence to rubbish. Add I’M for the writer’s
9 Amount of herring from end of harbour tinned (4)
CRAN You either know it or have learned it today. 37½ gallons, for what it’s worth. If the end of harbour is tinned it is in CAN
10 Hugest new dwelling by river that can accommodate visitors (10)
GUESTHOUSE Hugest “new” gives you GUESTH which leaves you to find the river OUSE. Chambers has it hyphenated.
11 Ruler who lost his head leading fashionable people a dance? (10)
CHARLESTON A generous historical reference, Charles 1 being the executed monarch as any fule kno. TON, more often just fashion but OK as people of fashion, is tagged on for Strictly’s favourite dance.
13 Baddie’s heading off to create this? (4)
EVIL Baddies don’t come more bad than the/a DEVIL. Do unto him as Richard Brandon did unto Charles 1 (probably) and you produce the Devil’s creation.
14 Isolated fellow who handled Sherlock Holmes stories? (8)
STRANDED You need to know that Arthur Conan Doyle published many of the Sherlock stories in the Strand magazine, so was handled by the STRAND ED.
16 Property — idiots may keep theirs, at first (6)
ASSETS Idiots are ASSES, insert T from Theirs “at first”
18 Sluggish swim with rubbish around (6)
TORPID Swim is DIP, RUBBISH is ROT, concatenate and reverse “around”
20 Scholarly story about the heartless scoundrel (8)
LITERATE Story here is LIE, which takes position about both heartless T(h)E and scoundrel RAT.
22 Stone circle west of China (4)
OPAL Circle O, to be placed west (to the left of) PAL for China (CRS China plate, mate. But you knew that.)
24 Church about to be given sums of cash for formal events (10)
CEREMONIES Church: C(of)E, about: RE, sums of cash MONIES.
26 Like prescription and wrong pills coming from mad chemist possibly (10)
MISMATCHED If you get the wrong pills in response to your prescription... The anagram needed (“possibly”) is from MAD CHEMIST. Well matched definition and wordplay.
28 Irishman knocking over post (4)
29 Still cold when wearing heavy material (6)
PLACID C(old) enveloped in PLAID
30 Meeting with a suggestion as to how police might trap criminal? (8)
TRYSTING Amusing (unless you’re on the wrong end). The Police might be encouraged to TRY (a) STING to catch the bad’ns
2 Throat gel worked quite slowly (9)
LARGHETTO An anagram (“worked”) of THROAT GEL for the adequately described musical term.
3 After short time whale is seen in holiday location (7)
MINORCA Short time is min(ute, of course) and whale is ORCA
4 Music concert group of countries set up (5)
GIGUE Concert is GIG, and the "set up" group of countries is the EU.
5 According to radio, precipitation is expected (3)
DUE Sounds like DEW, precipitation.
6 Manager occupying temporary accommodation, desperate man stuck inside (9)
INTENDANT Apparently more common in forn parts. Occupying temporary accommodation is IN TENT, insert Desperate DAN of the Dandy
7 Sea god, fat, yellow and soft, surfacing (7)
PROTEUS As well as being a variety of Greek heroes, Proteus is indeed a Sea god, rather fetchingly composed of SUET (fat), OR (yellow) and P (soft, in music). “Surfacing” in the down clue is your reversal indicator
8 Dodgy behaviour with greeting — there may be something fishy here (5)
SUSHI Dodgy (with or without behaviour) is SUS, and the greeting HI.
12 Alcoholic drink not quite right for child (7)
TIDDLER is the preferred answer. TIDDLEY is your drink, more often tiddly and more often (in your commentator’s opinion) an adjective (drunk) rather than a noun (drink). Take away the end, add an R and you get our answer, more often a small fish or a generic small thing. TODDLER, which I confidently entered, is (IMHO) more obviously a child, but lacks the advantage of having a drink spelled TODDLE?. The nearest I can get is toddy, which doesn’t work.
15 Firm is old-fashioned, keeping order mostly (9)
DEDICATED Old fashioned is DATED, insert EDIC(t) for your almost complete order
17 Renegotiated rent a bit high ultimately for old country building (5,4)
TITHE BARN An anagram (“renegotiated”) of RENT A BIT plus the last letter of higH
19 Controversial European means to be heard by audience (7)
POLEMIC Our European of choice is a POLE, and a MIC would help him to b heard.
21 Bit of hair giving girl, ten, makeover (7)
RINGLET An anagram (makeover) of GIRL TEN
23 Bottle — something kept in a cabinet, might you say? (5)
PHIAL Our second sound alike clue, this time “file”
25 High time to discard a blouse (5)
MIDDY Midday is high as in noon. Throw away the A for a “loose blouse worn, esp formerly, by women and esp children, having a collar with a broad flap at the back in the style of a sailor's uniform”. Thank you Chambers.
27 Bowler maybe who gets opener dismissed (3)
HAT Who translates to THAT, from which the “opener” is removed.