ACROSS
6. (CONDOMINIUM AC)* = INCOMMUNICADO <off the grid>
9. <dessert> CHURROS = (CHARLOTTE RUSSE)* - SEATTLE*
10. <student accommodation> HALLS = HAS outside LL
11. NO IS _E = NOISE <interference in signal>
12. <&-lit> DOUBLE-U = (_D_ + _OU_) BLEU
14. <picturesque> IDYLLIC = ←(...s)CILLY DI(s...)←
16. <things said> DICTA = ←AT CID←
17. V inside UU + L_A = UVULA <hanger>
19. "BOO K" = BOUQUET <scent>
20. ←DIS← ESP LITTERS = SIDE-SPLITTERS <they're extremely funny>

DOWN.
1. <shuts down> DISCONTINUES = DISCO + IN inside TUNES*
2. "SCREW TINNY" = SCRUTINY <critical observation>
3. "MUST" = MUSSED <somewhat out of place>
4. WIT + (HUB outside OUTDO) T = WITHOUT DOUBT <for sure>
5. <bombardment> HAIL = "HALE"
7. ←(...s)ESI ALLIES RAM(b...)← = MARSEILLAISE <national anthem>
8. SUBTRACTIONS* = OBSCURANTIST <made intentionally hard to understand>
13. T inside CRUELER* = LECTURER <teacher>
15. <metallic element> COBALT = COLT outside BA_
18. "ERR DO" = URDU <talk of Karachi>