ACROSS
 1. WAR RAN + TOFF IC ←RE← = WARRANT OFFICER <serviceman>
 9. OUTER EAR outside W = OUTERWEAR <Ulster?>
10. IP inside PER = PIPER <musician>
11. PA'S TRY = PASTRY <dough>
12. CHE CH N_ Y_ A_ = CHECHNYA <Caucasus republic>
14. RAVIN[-g] outside (I BO F_ L_) = RIBOFLAVIN <vitamin B₂>
16. ←IF← + RM = FIRM <company>
18. PU off PUMICE = MICE <quarry for queen?>
19. <Busted number> AIR HOSTESS = OTHERS* inside A _IS_ _S_
22. <continuing to make noise> RESONANT = RE SON ANT
23. SITCH outside _T = STITCH <bit of needlework>
26. <get> GRASP = G + RASP
27. INCUR IOUS = INCURIOUS <without interest>
28. <Victorian author> CHARLES DICKENS = ARLES D inside CHICKENS

DOWN
 1. <blatant lie> WHOPPER = WHO + UPPER - U
 2. <judges> RATES = RATS outside E
 3. AI + RC RAFT = AIRCRAFT <plane, perhaps>
 4. <pronoun> THEM = (THE M)
 5. <plainspoken> FORTHRIGHT = FORTNIGHT, HR←N_
 6. <consequence> IMPACT = I'M PACT
 7. <dear> EXPENSIVE = EX PENS (V inside IE)
 8. (GRO[-o]MS)* outside _A = ORGASM <climax>
13. (I AID NEWTON)* = NATIONWIDE <English financial institution>
15. <character> BACKSLASH = →"SLACK BASH"←
17. <secret> ESOTERIC = [-b]ES[-t] [-h]OTE[-l] [-p]RIC[-e]
18. MAGE outside IR = MIRAGE <illusion>
20. SCH SMS outside I = SCHISMS <religious divisions>
21. <offer that aims> SNIPER = SNIP _E _R
24. TROUPE - U = TROPE <theme in storytelling>
25. <eliminated> ICED = ⭯DICE⭯