Across:
1 In conclusion (RESULT), boss (= anagram indicator) rules (rules = RESUL-) roost ultimately (‘roosT’ ultimately = -T) (RESULT),
4 They usually pull their hair out (BANSHEES) with howlers (BANSHEES),
9 Drink (SHERRY) the last of the Rieslings (last of the ‘rieslingS’ = S-) with German gentleman (-HERR-) getting tipsy at The Foundation (getting ‘tipsY’ at the foundation = -Y) (SHERRY),
10 Point (compass point South = S-) from newspaperman (-PRINTER) (SPRINTER) is certainly a runner (SPRINTER),
12 Vegetable (ARTICHOKE) and haricot (haricot) stew (= anagram indicator) (haricot = ARTICHO-) from Kildare (-KE) (ARTICHOKE),
13 Turns up (= reverse indicator), so (so = -OS) alike central (‘aLIKe’ central = lik = (KIL-) (KILOS) figures the guards mention in a drugs bust (KILOS of drugs),
14 The Paper’s (the papers/sheets = SHEETS) after (= position indicator) 27 across (‘charge’ = CHARGE) (CHARGE SHEETS) with lists of accusations (CHARGE SHEETS),
18 Time (T-) is right (-R-) to stop (-END-) making a scene (-SETTING) (TRENDSETTING) as everyone is following it (TRENDSETTING),
21 Literally throws away tray (‘literally’ throws away ‘tray’ = liell = LILLE) from French city (LILLE),
22 Incomplete (e) cell (‘spore’ without ‘e’ = SPOR-) at college (-C-) consumed by old despot (Tsar = -TS -AR) (SPORTS CAR) in fast vehicle (SPORTS CAR),
24 For the final (= position indicator), relative (son = -S ON) is no longer in (passé = PASSE-) (PASSES ON) relays (PASSES ON),
25 Volunteers dropped, sent (‘volunteers’ dropped ‘sent’ = voluer = LOUVRE) to a foreign art museum (LOUVRE),
26 Place (SET-) on a (-A-) team (-SIDE) (SET-ASIDE) for reserve (SET-ASIDE),
27 Resist taking from cash register (‘resist’ taking from ‘cash register’ = cahger = CHARGE) – the judge will see you about this (CHARGE).
Down:
1 Groundwork (RESEARCH) for showing off (= anagram indicator) cars here (cars here = RESEARCH),
2 It’s like the spirit (SPECTRAL) of Carl’s pet (Carls pet) cuckoo (= anagram indicator) (Carls pet = SPECTRAL),
3 Station (LYRIC) Ted came from directly (‘Ted’ came from ‘directly’ = ircly = LYRIC),
5 Agency (Associated Press = AP-) upsets (= reverse indicator) that woman (her = -REH-) consumed by retirement plan (pension = -P-ENSION) (APPREHENSION) with butterflies in her stomach (APPREHENSION),
6 Carry on (STICK AT IT) Sergeant – the first (‘Sergeant’ the first = S-) to locally credit (‘locally’ credit = -TICK) a (-A-) bird (bird = -T-IT) (STICK AT IT),
7 Sings the praises of (EXTOLS) mystery woman (-X-) in lace (= anagram indicator) stole (stole = E-TOLS) (EXTOLS),
8 Can’t make this point strongly enough (STRESS) – this could break your heart (STRESS),
11 Accept orders (DO AS ONE’S TOLD) for parties (dos = DO -S) across America (A-) from individuals (ones = ONE’S) who spilled the beans? (TOLD) (DO AS ONE’S TOLD),
15 Adam (GARDENER-) Smith, the first (‘Smith’ the first = -S) (GARDENERS) of those pandering to The Greens perhaps (GARDENERS),
16 Figure out (DISCOVER) of nightclub (DISCO-) upsetting (= reverse indicator) minister (Rev = -VER) (DISCOVER),
17 Distress (AGGRIEVE) in the street (A-VE) over horse (-GG-) from Ireland (Eire) almost (e) (‘Eire’ without ‘e’ = eir) falling over (= reverse indicator) (eir = -RIE-) (AGGRIEVE)
19 Gets lover to run in tandem (ELOPES) The European (Pole) Review (= reversal indicator) (Pole = ELOP-) and starts Evening Star (starts ‘Evening Star’ = -ES) (ELOPES).
20 Press (CLOSET) to cease production (close = CLOSE-) at the end of it (at the end of ‘iT’ = -T) (CLOSET),
23 Ned leaves on the dot (‘Ned’ leaves ‘on the dot’ = othot = TOOTH) with canine (TOOTH).