ACROSS
1. CONS PI + RACIST = CONSPIRACIST <truther>
8. I DIM outside O = IDIOM <artistic style>
9. _R ←AGO← (J inside NOSH) = ROGAN JOSH <Kashmiri dish>
11. A BEYONCE, O→A = ABEYANCE <bit of time off>
12. FAVE LA = FAVELA <shanty town>
14. GAS P = GASP <sudden burst of inspiration? {i.e. intake of breath}>
16. <avoid school> PLAY TRUANT = (TUNA PARTLY)*
18. AS inside (-m)EMPHIS ED = EMPHASISED <stressed>
19. "BLEW" = BLUE <pornographic>
21. <one fishy...?> TURBOT = TURBO T
22. <stuck> ANCHORED = AND outside CHORE
25. <be suspicious> SMELL A RAT = MASTER* outside ←ALL←
26. <fake> FEIGN = FE _N outside IG
27. (SUCH FOODS ARE)* = HOUSE OF CARDS <flimsy set-up>

DOWN
1. C HIDE = CHIDE <reprimand>
2. NUMB A_T = NUMBAT <marsupial>
3. PORT CULL IS = PORTCULLIS <grating>
4. <go ballistic> RAGE = RE outside AG
5. ETRUSCAN* = CENTAURS <creatures of myth>
6. STALL outside (ONE W) = STONEWALL <to prevent progress>
7. <they dress> VINAIGRETTES = ←SETTER + GI← after VAIN*
10. <excruciating> HEART-RENDING = HEAR TRENDING
13. (-anne)CY-BERN E-TIC(-ket) = CYBERNETIC <using automated systems>
15. <perhaps someone powered> SUPERHERO = S EUROPE* outside RH
17. C_ A_ (O inside GULES) = CAGOULES <waterproof jackets>
20. <ceremonial trumpet> SHOFAR = (SO FAR) outside H
23. (-c)R(-e)A(-t)I(-o)N(-i)S(-t) = RAINS <what cause the Flood?>
23. (-commiss)AR CO(-urteously) = ARCO <with a bow>