1: Unbelievable boast in part of the castle (7)
5: Got crazy, wearing feathers in colony of rodents (3,4)
9: Drive away roofing material before farmhouse becomes a target area (8,5)
10: Ancient Semitic deity like very sour egghead (7)
11: Will addition show 100 + 0 + 500 + 99 + 49? (7)
14: Does the wandering hero duly hostess perplex? (7)
15: Inflexible yet adjusted (3)
16: Odds of niece being born (3)
18: Drunkard turns up near beach, reversing new habit, to sleep fitfully (4,3,4)
21: Late, reflective Freud revolting, in part (7)
22: Tar mess contaminated rivers (7)
24: Ball-horses are travellers! (5-8)
26: Spas misplaced rosters (7)
27: Praised muck in supplement (7)