Across:
1 Offshoot (BRANCH) of female support (BRA-) for concert hall (National Concert Hall = -BRA) (BRANCH),
4 At the end of 14 across (‘test the water’ = WATER), enfant terrible (brat) loses the head (‘brat’ without ‘b’ = RAT) (WATER RAT) with beastly type of good swimmer (WATER RAT),
9 Portion of the lamb (CUTLET) graze (CUT-) by the temporary accommodation (-LET) (CUTLET),
10 Peter’s out (EBBS AWAY) of English (E-) hostelry (B&B = -BB-) and going south (-S) on holiday (AWAY) (EBBS AWAY),
12 Local subsidises (BANKROLLS) those with the dough (BANK-) for the baps and blaas (-ROLLS) (BANKROLLS),
13 Swore (swore = WORSE) badly (= anagram indicator), as it’s not getting any better (WORSE),
14 Market research? (TEST THE WATER) Go take a running jump! (TEST THE WATER),
18 What a successful bounty hunter might do (CLAIM A REWARD) with allegation (CLAIM) by American (A) in 7 down (‘reward’ = REWARD) (CLAIM A REWARD),
21 Hostile force (ENEMY) in unstable (= anagram indicator) Yemen (Yemen = ENEMY),
22 Irish love (Irish ‘love’ = grá = GR- -A-) consuming food (-EAT S-) with the last of the vintage (with the last of the ‘vintage’ = -E-) port (left = -L) (GREAT SEAL) or Harp in Ireland, for instance (harp stamped into wax / GREAT SEAL),
24 Crucial (crucial = CIRCULA-) play (= anagram indicator) with right (-R) (CIRCULAR) message for wider distribution (CIRCULAR),
25 Foolish figure (ASS-) first (1st = -IST) (ASSIST) to help (ASSIST),
26 It’s feedback (RESPONSE) thanks be to God (‘thanks be to God” = RESPONSE),
27 The Examiner (TESTER) is looking for evidence of a bad habit? (TESTER).
Down:
1 Talk nasty about (BACKBITE) support (BACK-) for Sting (sting = -BITE) (BACKBITE),
2 Shock (ASTONISH) as Martin’s travelling companion (ASTON- Martin car) is (-IS-) going to hospital (-H) (ASTONISH),
3 Heretic loses it (‘heretic’ loses ‘it’ = CHEER) with Joy (CHEER),
5 Hasn’t a minute to spare (AS BUSY AS A BEE) to describe work ethic of the honey producers (AS BUSY AS A BEE),
6 English (E-) novice (learner = -L-) gets stitch (-SEW-) on this spot (-HERE) (ELSEWHERE) or another place (ELSEWHERE),
7 Agitated (= anagram indicator) warder (warder = REWARD) gets compensation (REWARD),
8 Herb’s (herbs = THYMES) jazz (= anagram indicator) myths (myths = THYM-S) about One Direction (east = -E-) (THYMES),
11 They’re designed for those approaching retirement (SLEEPING BAGS) or for those pitching temporary accommodation (SLEEPING BAGS),
15 See! (TOLD YOU SO) Don’t say I didn’t warn you (TOLD YOU SO),
16 The truth (fact = FAC--T) about Sporting (reversal indicator) Life (life = -ELIF-) (FACELIFT) – it might give you a smile, cosmetically speaking (FACELIFT),
17 Worships images (IDOLATER) of tailored (tailored = IDOLATER) dress (= anagram indicator),
19 Local dealer (FENCE-) is right? (-R) (FENCER) He’s the type of guy presumably used to sabre-rattling (FENCER),
20 Refuse (refuse/rubbish = DEBRIS) to upset (= reversal indicator) polite chap (Sir = -RIS) at base (base = bed = DEB-) (DEBRIS),
23 The sense (one of the senses = TASTE) to compliment a stewardess inside (“compliment a stewardess” inside = TASTE).