Easy
15A Supporter of a controversial idea (9) A ? ? ? O ? I ? T
18A Lacking competence (8) I ? E ? ? ? R ?
14D Grumble, moan (8) ? ? ? ? ? A ? N
Cryptic
15A Flight that sometimes continues after landing (9) S ? ? ? R ? A ? ?
18A Unflagging, sister about to entertain the French (8) ? ? R ? ? ? S ?
13D Knock it back in Iceland, brewd just the same (9) I ? ? ? D ? ? ? ?
16D Emotionless time, entering hard (6) ? ? ? L ? D
20D City centre dawdle (4) ? S ? ?