Across:
1 High Courts extracted this (‘high courts’ without ‘this’ = hgcour = GROUCH) from a fault-finder (GROUCH),
4 In 14 across, starts (starts ‘hard to please’ = HARD) and jobs, in the metaphorical sense (HATS) (HARD HATS), for those working on the sites locally (HARD HATS),
9 Let off the hook (EXEMPT) by former partner (EX-) and is mostly (y) unoccupied (‘empty’ without ‘y’ = -EMPT) (EXEMPT),
10 Answer (A-) trivia (trivia) question (= anagram indicator) (trivia = -VIATRI-) wrong (-X)? (AVIATRIX) Presumably, Amelia Earhart had a job getting it! (dated word for a female pilot = AVIATRIX)
12 Stick to one’s guns (SOLDIER ON) in the army (SOLDIER) going forward, in a timely sense (ON) (SOLDIER ON),
13 Graceful type of carriage (graceful body deportment = LITHE) found in some moonlit heartland (found in some ‘moonLIT HEartland’ = LITHE),
14 It’s not easy (it’s HARD) getting best (top = -TO P-) rental (-LEASE) (HARD TO PLEASE) in particular (particular = HARD TO PLEASE),
18 Characters in 21 across (‘hardy’ = HARDY) associated with yearbooks (ANNUALS) (HARDY ANNUALS) of bells of Ireland, for instance (“Bells of Ireland” plants = HARDY ANNUALS),
21 It’s tough (HARDY) opening 14 across (opening ‘hard to please’ = HARD-) close to facility (close/end to ‘facilitY’ = -Y) (HARDY),
22 Artist (TATTOOIST) in tasteless clothes (TAT-) is also (-TOO-) the earliest to arrive (first = 1st = -IST) (TATTOOIST),
24 At the start of thunderstorm (on top of ‘Thunderstorm’ = T-) with swirling current (whirlpool = -EDDY), sea guide (buoy) listens (= homophone indicator) (“buoy” = “boy” = BOY) (TEDDY BOY) to Elvis impersonator (TEDDY BOY),
25 Straight and narrow (LINEAR) bar (LINE-) for a (-A-) final beer (final ‘beeR’ = -R) (LINEAR),
26 Is (-IS-) found in exhibition (exhibition/parade = PARAD-E) (PARADISE) of Utopia (PARADISE),
27 In the autumn (SEPT-), one (-I-) cold (-C) (SEPTIC) could be infectious (SEPTIC).
Down:
1 Shot in the dark (GUESS) by health care professionals? (World Health Organisation = WHO) (GUESS WHO) That’s a question for those who are blinkered! (GUESS WHO),
2 Former chief (OVERLORD) designed (= anagram indicator) old Rover (old Rover = OVERLORD)
3 Mediterranean island (CAPRI) hogs removed from cargo ship (‘hogs’ removed from ‘cargo ship’ = carip = CAPRI),
5 Promote (ADVANCE) Jamboree (PARTY) (ADVANCE PARTY) for The Scouts (ADVANCE PARTY),
6 Excellent local (‘excellent’ locally/informally = DEADLY!) school (S-) is popular (-IN) (DEADLY SIN), producing envy (DEADLY SIN),
7 Add a touch of sparkle (sparkle/bubbles = AERATE) as Judge (-RATE) Russell (AE-) is up first (= position indicator) (AERATE),
8 Group of players (SEXTET) in first eleven (first ‘Eleven’ = -E-) chasing (= position indicator) goals ultimately (‘goalS’ ultimately = S-) at times (-X-), for starters, for the English team (starters on ‘The English Team’ = -TET) (SEXTET),
11 Middle Eastern (middle ‘easTern’ = T-) agent (-REP-) working to attract foreign direct investment? (Industrial Development Authority = -IDA-) It’s no (its no) joke (= anagram indicator) (its no = -TIONS) (TREPIDATIONS) in troubled states! (troubled states = TREPIDATIONS),
15 Lachrymose (TEARY-EYED) politician (T-D) conceals listening device (-EAR-) twice for first two years (first two ‘YEars = ‘ye’ twice = yeye = -Y-EYE-) (TEARY-EYED),
16 Graduate (MA-) produces (= anagram indicator) finest (finest = -NIFEST) (MANIFEST) display (display/show = MANIFEST),
17 Recites (recites) novel (= anagram indicator) (recites = ES-TERIC) about love (-O-) (ESOTERIC) stuff that’s puzzling to most (ESOTERIC)
19 Contrary to 23 down (SHUT UP is contrary to ‘opine’) this is a restraining order (SHUT UP),
20 Introduce coffee (introduce ‘Coffee’ = C-) that’s less refined (-RUDER) (CRUDER) and more rough and ready (CRUDER),
23 Policeman emits calm (‘policeman’ emits ‘calm’ = poien = OPINE) in hazard, in a manner of speaking (hazard a guess / give opinion = OPINE).