Across:
1 Suits (playing cards = HEARTS) those in 13 across (‘heart’ = HEART-) on open sea (open ‘Sea’ = -S) (HEARTS),
4 Make scene (ST-AGE) over old (-O-) father (Father/Parish Priest = -PP-) (STOPPAGE) downing tools (STOPPAGE),
9 “Rebellious (= anagram indicator) Utah or (Utah or = AUTHOR) Tennessee” (Williams), for example (Tennessee Williams = AUTHOR),
10 Alaska (AK-) tanks (-VA-TS) hold six (-VI-) (AKVAVITS) bottles of poitín way up north perhaps (Scandinavian spirits = AKVAVITS),
12 Precious sort (silver = AG-) gets a (-A-) note (staff note/ memo = -MEM-O-) about new (-N-) point (compass point North = -N) (AGAMEMNON) produced by old Greek commander (AGAMEMNON),
13 Epicentre (HEART) of earth (earth) quake? (= anagram indicator) (earth = HEART),
14 Open conversation (HEART-TO-HEART) with most of 1 across (‘hearts’ = HEART) and half the town (half the ‘TOwn’ = -TO -) in 13 across (‘heart’ = HEART) (HEART-TO-HEART),
18 Musician’s (musicians = GROUP) electronic (-E-) music (-RAP- music) in your old (‘your’ old = thy = TH-Y) (GROUP THERAPY) treatment that’s not exclusive (GROUP THERAPY),
21 Rule (REIGN) from base off Bering Sea (‘base’ off ‘Bering Sea’ = ering = REIGN),
22 Woman (APRIL) taking local dope (local ‘dope’ = FOOL) (APRIL FOOL) is the butt of a joke (APRIL FOOL),
24 Jolly Roger (FLAG-) moves pirates on the high seas (-SHIP) (FLAGSHIP), as it’s the most important of its kind (FLAGSHIP),
25 Relative (Ma) keels over (= reverse indicator) (Ma = -AM) unfortunately (alas), going back (= reverse indicator) (alas = SALA-) (SALAAM) to take a bow (SALAAM),
26 What Teddy has to look through perhaps (BEADY EYE) with a hostile little pupil (BEADY EYE),
27 Discredit (DEMEAN) Madeleine dismissing lie (‘Madeleine’ dismisses ‘lie’ = madene = DEMEAN).
Down:
1 Source of irritation (HEADACHE) for man (HE-) from Dacha (Dacha) showing off (= anagram indicator) (Dacha = -ADACH-) energy (-E) (HEADACHE),
2 Part of the column (ASTRAGAL = part of an architectural column) is to do with the stars (astral = ASTRA-L) including legend (‘leG’ end = -G-) from America (-A-) (ASTRAGAL),
3 The irony is (TROPE), spectator is missing cast (‘spectator’ is missing ‘cast’ = petor = TROPE),
5 Two signs (token + gesture = TOKEN GESTURE) – one of them symbolically meaning nothing (TOKEN GESTURE),
6 Gym (PE-) teacher (teacher) out (= anagram indicator) (teacher = -ACH TREE) (PEACH TREE) in the orchard (PEACH TREE),
7 Certain to get away from Latin-American (‘certain’ to get away from ‘Latin-American’ = lamian = ANIMAL) tapir, for example (ANIMAL),
8 Not genuine (a substitute = ERSATZ) rates (rates = ERSAT-) laid out (= anagram indicator) for the last of the fizz (last of the ‘fizZ’ = -Z) (ERSATZ),
11 A foreign (a = UN-), well-liked (-POPULAR-) metropolis (city), needs no introduction (‘city’ without ‘c’ = -ITY) (UNPOPULARITY) in a state that’s not hot (UNPOPULARITY),
15 What would Dr Jekyll do suddenly (TURN NASTY as Mr Hyde) to change direction (TURN) on a (-A-) street (-ST-) in New York? (NY = N-Y) (TURN NASTY),
16 Bulldoze (shove/barge = BAR-GE) over tops of outstanding natural area (tops of ‘Outstanding Natural Area’ = -ONA-) (BARONAGE) for noble folk (BARONAGE),
17 A (-A-) Frenchman (Monsieur = -M-) in Revolution (revolution = cycle = CYCL-E-) is not the first (‘Not’ the first = -N) (CYCLAMEN) plant (CYCLAMEN),
19 Digs up (= reversal indicator) iron (Fe = -EF-) bar (bar = -R-AB) found outside park (P-) (PREFAB) by building in temporary setting (PREFAB),
20 Bug (CICADA) in police department (Criminal Investigation Department = CI-D) captures assistant commissioner (Assistant Commissioner = AC) backtracking (= reversal indicator) (AC = -CA-) on answer (-A) (CICADA),
23 Longs to get out of Los Angeles (‘longs’ to get out of ‘Los Angeles’ = aeles = LEASE) with contract for Homeland, perhaps (LEASE).