No 12406, Monday 27 Aug 2018, Anon

ACROSS
1   Team up with officer at workplace to sermonise (11) COLLABORATE {COL}{LAB}{ORATE}
9   Wide, say, caught in passage (7) EXTRACT {EXTRA}{CT}
10 Passed recess in empty land (6) LAPSED {Lan{APSE}D}
11 Curt tribal leader starts off poem (5) TERSE {Tr...l}{vERSE}
12 Tyrannise, partly stop journalists (7) OPPRESS {stOP}{PRESS}
15 Alien receives regular bans in the Orient (4) EAST {E{bAnS}T}
16 Premium pen entangled in vine (10) EPIPREMNUM*

18 Reduced agreement with journalist (10) CONTRACTED {CONTRACT}{ED}
20 Leaders smash convict’s arm, raze mark (4) SCAR Acrostic
23 Get together for prayer (7) COLLECT [DD]
24 Group of Hindus in Bulgarian city (5) VARNA [DD]
26 Returning European, journalist ran away (6) ELOPED {POLE<=}{ED}
27 King confused Roman at church (7) MONARCH {ROMAN}*{CH}
28 Find out about sectarian journalist (11) ASCERTAINED {SECTARIAN}*{ED} Should have been 'Found out'

DOWN
2   Trebuchet for ass (6) ONAGER [DD]
3   Removes source of toxin from coffee at last minute (4) LATE LAtTE
4   Girl reported attack on capsicum? (4,6) BELL PEPPER (~belle){BELL} {PEPPER}
5   Newsman to empty rye beer (8) REPORTER {RyE}{PORTER}
6   Betrayal without final cause (7) TREASON {w...uT}{REASON}
7   Awareness of one in punishment (9) SENTIENCE {SENT{1}ENCE}
8   Gazes at steps, we hear (6) STARES (~stairs)
13 Simpleton to order trainee (5,5) SPACE CADET {SPACE} {CADET}
14 Hindu god returns, hasn’t mashed grains (9) AMARNATHS {RAMA<=}{HASNT}*
17 Fall out of place by professional’s mistake (8) PROLAPSE {PRO}{LAPSE}
19 Pastas for dimwits (7) NOODLES [DD]
21 Medicine contains odd Afro muscle relaxant (6) CURARE {CUR{AfRo}E}
22 A locale with boulevard (6) AVENUE {A}{VENUE}
25 Zulu regiment traps politician within Israeli limits (4) IMPI {Israel{MP}I}

GRID