Across:
1 Hector (hector/jeer = -BOO-) found in bar (BA-N) (BABOON) with primate (BABOON),
4 Great local (‘great’ locally = SMASHING) craic (‘craic = ‘crack’ = SMASH-) overheard (= homophone indicator) in (-IN-) Government (-G) (SMASHING),
9 Brought up (REARED) by novel (= anagram indicator) reader (reader = REARED),
10 A French (a = UN-) way of acting (manner) curtailed (r) (‘manner’ without ‘r’ = -MANNE-) by director (-D) (UNMANNED) having no crew (UNMANNED),
12 Faithfulness (CONSTANCY) of canny Scot (canny Scot = CONSTANCY) showing off (= anagram indicator),
13 Trainee (learner = L-) soldier informally (sergeant = sarge) loses head (s) (‘sarge’ without ‘s’ = -ARGE) (LARGE) with major (LARGE),
14 Local foolish person (GOOSE) spots (PIMPLES) (GOOSE PIMPLES) signs of excitement (GOOSE PIMPLES),
18 Monitor (SCREEN-) hack (-WRITER) (SCREENWRITER) who produced The Script? (SCREENWRITER),
21 Understood (KNOWN) this is in the public domain (KNOWN),
22 Tramp (TREAD-) is presumably responsible for generating rumours (rumour -MILL) (TREADMILL) of the boring routine (TREADMILL),
24 Clothing collection (WARDROBE) for awful (= anagram indicator) bad rower (bad rower = WARDROBE),
25 Unimportant to dismiss Trump (‘unimportant’ to dismiss ‘Trump’ = nioant = NATION) in the US, for example (NATION),
26 Revolutionary (RED-) played a part (-ACTED) (REDACTED) and was taken out by keyboard warrior perhaps (REDACTED),
27 Mixes (MERGES) with son from Moss Green (‘son’ from ‘moss green’ = msgree = MERGES).
Down:
1 Company leader (‘Company’ leader = -C-) in rough (= anagram indicator) brigade (brigade = BIRD-AGE) (BIRDCAGE) is capable of containing The Hawks (BIRDCAGE)
2 Fight (B-OX) over state (= homophone indicator) rule (‘reign’ = ‘rain’ = -RAIN-) by blockhead (‘Block’ head = -B-) (BRAINBOX) or clever clogs (BRAINBOX),
3 Is out there (OVERT) to lift lid off (c) secret (‘covert’ without ‘c’ = OVERT),
5 Lucrative enterprise (MONEY-SPINNER) in capital (MONEY) for evildoer (S-INNER) handling pressure (-P-) (MONEY-SPINNER),
6 A large one? No, but you can ask the barman for it (SMALL BEER) – by comparison, it’s not worth much! (SMALL BEER),
7 Don’t bring any attention to (IGNORE) Gore in (Gore in = IGNORE) trouble (= anagram indicator),
8 Stage-managed without means – a (‘stage-managed’ without ‘means a’ = tgeagd = GADGET) labour-saving innovative device (GADGET),
11 Single (I-) note (-N-) on summary (-DIGEST-) from lawyer (-BL-) in Ireland (Ireland domain = .ie = -I-E) (INDIGESTIBLE) is too complex to read (INDIGESTIBLE),
15 Free spirit (ECCENTRIC) for community (European Community = EC-) copper (-CENT-) from old police force (Royal Irish Constabulary = -RIC) (ECCENTRIC),
16 Is not working (STRIKING) or achieving one’s goals (scoring goals = STRIKING),
17 Drunk (= anagram indicator) a pilsner (a pilsner = PRALINES) tasting sweet like nuts wrapped up in chocolates (PRALINES),
19 Turns up (= reversal indicator), needs to get to Bath badly (needs to get to bath badly/reeks = SKE-ER) over the start of the weekend (the start of the ‘weekend’ = -W-) (SKEWER) for barbecue (SKEWER),
20 Dirt or (dirt or = TORRID) ground (= anagram indicator) can be hot (TORRID),
23 Drop (DRAPE) of DNA taken from red panda (‘DNA’ taken from ‘red panda’ = redpa = DRAPE).