ACROSS
 9. <London thoroughfare> WHITECHAPEL ROAD = W HI-TECH APE LOAD outside _R
10. <peers> DUKES = D_ UKES
11. HISTORY* in F_A = FORSYTHIA <bush>
12. M_ YOLO GIST = MYOLOGIST <one working on muscles>
13. <cut> MOWED = "MODE"
14. DEMO TIC = DEMOTIC <vulgar>
16. →"FLED RAG"← = RED FLAG <cause for concern>
18. <Brit> LIMEY = "LIE ME"
20. (.i)MON'S TROUS(e.) = MONSTROUS <awfully huge>
22. (MIT FROSH)* outside X = SIXTH FORM <college>
24. <oaf> = A N out of ANTWERP
26. M + (EX I CAN STAND) OFF = MEXICAN STANDOFF <impasse>

DOWN
 1. <outstanding> OWED = "ODE"
 2. (WORKS MIL_)* = SILKWORM <fibre producer>
 3. NEW (WRY HOST)* = NEWSWORTHY <fit for a reporter?>
 4. <butcher's> SHUFTI = (FISH _UT_)*
 5. <I put people through> OPERATOR = PE inside ORATOR
 6. <perform> PLAY = P LAY
 7. <guest not attending> NO-SHOW = NOSH OW
 8. ED ←SAGE DRAG← = EDGAR DEGAS <artist>
12. <interfering> MEDDLESOME = (SOD LED)* inside MEME
13. MEDIATING outside T = MEDITATING <thinking>
15. <chemical> COMPOUND = CO MOUND outside P
17. <I watch> LOOKER-ON = K inside LOO + NERO*
19. <Brazilian dance> MAXIXE = MA + XIX _E_
21. <halfwit> NUMPTY = MP inside NUT Y
23. <white> HOCK <pawn>
25. PU F_ + F = PUFF <burst of gas>