Across:
1 Taster (SAMPLE) meals (meals = SAM-LE) prepared (= anagram indicator) around park (-P-) (SAMPLE),
4 Playing (= anagram indicator) on cellos (on cellos = COLONELS) or working on the base? (COLONELS working on army base),
9 A measure of the newspaperman (LINAGE) with head barman (attorney general = -AG-) in bar (LIN-E) (LINAGE),
10 Without warning, moves (UP STICKS) parking (-P) for staff (staff/rod = STICK-) in America (US = U- -S) (UP STICKS),
12 What one of the beach bums might take (DECK CHAIR) from Grace (grace/enhance = DECK) Chesterfield? (Chesterfield sofa/seat = CHAIR) (DECK CHAIR),
13 Look (EY-E) over rental income tips (‘Rental Income’ tips = -RI-) (EYRIE) that might appeal to high flyers (EYRIE),
14 Dismissing (FIRING) those in Munster and Leinster, for instance (SQUADS) (FIRING SQUADS), they have well-defined targets they’re expected to hit (FIRING SQUADS),
18 Running (EXERCISE) with the first Bush (the first ‘Bush’ = B-) for American president (Dwight “Ike” Eisenhower = -IKE), (EXERCISE BIKE) – one might be put on the spot to work out? (EXERCISE BIKE),
21 Sound (AUDIO) of car (AUDI-) taking roundabout (-O) (AUDIO),
22 Gardaí have a job doing this? (DETECTION) The thieves have a job avoiding it! (DETECTION),
24 Driving hazard (BLACK ICE) in Belgium (B- -E) around the French (the = -LA-) border at Chimay (border at ‘Chimay’ = -C-) first of all kept in check (first of all ‘Kept In Check’ = -K IC-) (BLACK ICE),
25 In all decency (VIRTUE), sign (Victory sign = -sign) is primarily (‘Is’ primarily = -I-) not (= anagram indicator) true (true = -RTUE) (VIRTUE),
26 Energy (energy = GREEN-Y) running (= anagram indicator) around part of the hospital (-ER-) (GREENERY) produced by a number of plants (GREENERY),
27 Whilst it’s not in Welsh rarebit (‘whilst’ it’s not in ‘welsh rarebit’ = erareb = BEARER) or porter? (BEARER).
Down:
1 Got tough (SOLIDIFY) playing (= anagram indicator) idols FYI (idols FYI = SOLIDIFY),
2 Worker (MAN-) from old police force (RUC = -CUR-) retires (= reversal indicator) in Ireland (-I-E-) (MANICURE) – anyone who has had a nail-biting experience will appreciate it (MANICURE),
3 The reason (LOGIC) for police dog missing dope (‘police dog’ missing ‘dope’ = olicg = LOGIC),
5 They make the best of what happens (OPPORTUNISTS) to wild (= anagram indicator) sprouts in pot (sprouts in pot = OPPORTUNISTS),
6 Close to losing it (ON THE EDGE) with Cliff’s position (cliff is ON THE EDGE),
7 It’s just more (ENCORE) of what the fans asked for in the end (ENCORE),
8 Organisation (SYSTEM) produces mass hysteria dismissing Sharia (‘mass hysteria’ dismissing ‘Sharia’ = msyste = SYSTEM),
11 The man upstairs presumably (MASS-PRODUCER) is a man of the cloth? (MASS-PRODUCER),
15 Expect the hospital administrator will get this (NEXT OF KIN), as they’re all in The House presumably? (NEXT OF KIN),
16 Address for man (MI-STER) hanging around Ulster (-NI-) (MINISTER) churchman (MINISTER),
17 Comet (Comet is one of Santa’s REINDEER) seen in the sky once a year? (REINDEER),
19 A large brown beetle, also called a cockchafer (MAY BUG), might annoy (MAY BUG),
20 Online nuisance (ADWARE) using up (= reversal indicator) energy (-E) is fresh (fresh/ raw = -WAR-) for most of the day (most of the ‘day’ = da = AD-) (ADWARE),
23 Caught (C-) on the border (-RIM-) with drugs (-E) (CRIME) and is investigated by the guards (CRIME).