21a: without help from others (10) --A---S---
25a: keep from leaving (6) ------
27a: wear a long face (4) -O--
13d: not booked in advance (10) U-R-S-R---
15d: fanatics (10) E-T-----T-
17d: kitchen container for the stove (8) S---E-A-
22d: Australia's largest city (6) ----E-
26d: underweight(4) --I-