Solving time: 53:56 - Mainly being held up by 6 (didn't know the word) and 16 (struggled to decode the wordplay)

Looking back at it now, I think I must have been tired, since there don't seem to be any stinkers amongst the clues and the only word I didn't know was the one I've already mentioned.


cd = cryptic def., dd = double def., rev = reversal, homophones are written in quotes, anagrams as (--)*, and removals like this

Across
1	StAKE
3	MARASCHINO = MAR + CHINO about AS
9	ABYSMAL = LAMA rev about (BY + errorS)
11	OMNIBUS = US after (OM + NIB)
12	CROISSANT = C + ROT about (AS SIN)*
13	RA + BID
14	PERMEABILITY = LIT in (PIER MAYBE)*
18	BLACKCURRANT = (LACK + Country) in RUB rev + RANT
21	T(H)ORN
22	BAD + MINT + ON
24	RAP + PORT
25	MAY + Film + AIR
26	HE + ADS + ThRONG
27	PIT + Y
Down
1	SEASCAPE = CAP in (S + EASE)
2	KEYBOARD = (BOA + RD) after KEY
4	ALL + O + A
5	APOSTOLIC = (CLOTS + O + PA) all rev about I
6	CONFRATERNITY = CONFER about RAT + NIT + Y
7	IMBIBE = IE about (M + Barn In Britain)
8	ONSIDE hidden in 'Nations idelly'
10	MISCELLANEOUS = (ILL OMENS CAUSE)*
15	BACKBITER = BACK + (TRIBE)*
16	PASTRAMI = (PAST + I) about RAM
17	STINGRAY = (GRAIN)* in STY
19	ST + ARCH
20	HOOPLA = sHOO + ALP rev
23	DE(MO)N