Thanks all. Much appreciated.
I have some letters for Clue 17D.
Assumes in pretense (6)
? S ? L ? S
Stuck on the following...
4D. I 'm given an appointment as a duty (6)
I ? N ? S ?
16D. Go-ahead pawnbrokers may give you one. (7)
A ? ? ? T ? E
20A. Spring, often underground (5)
? ? U ? T