1: Inept casino confused the issue (4,2,5)
2: Chosen few travelled on with conductor (9)
4: Central matter for physicists luncheon: rocks releasing hydrogen (7)
5: When one should be expecting a suitable partner (3,4)
6: Charles talked about pictures of sea creatures (6,2,5)
7: Alternative part of course (5)
8: Mann's 'Death in Venice' Dorothy sent up (3)
10: Cat linked stories to the underworld (8-5)
14: Think at length about lost planet, comet (11)
17: Fashionable fragrance, fundamentally (2,7)
19: Raise vale. Tee off. (7)
20: Mad? O, yes! Mad dog! (7)
21: Denim -- a genuine clothing icon (5)
23: One may be transported by this kiss, it's said (3)