1: Unfathomable letters from Lamb, say (7)
2: Oxygen is pretty amusing. (3)
3: Fish spawn upstream in little orifices (3)
4: Auto manufacturer meeting a lieutenant in 'The Ancient Mariner'? (3,4)
5: Tinkers jump in children's world (3,4)
6: Celebration geared for retirement (6,5)
7: Singer Mel, not heartless, is suffering (7)
9: Alan, Timothy, and a couple of Estonians follow me at breakfast, lunch, and dinner (9)
11: Bright-sounding agenda touches on heavyweight legend (5,6)
12: Doctor singes off top of sore and bandages (9)
15: Initials of buddy in radio band (7)
16: Layperson to straighten us clear (7)
17: Pardon felon; it's over (7)
18: Empty country with iron or wood (7)
23: Consumed and digested tea (3)
24: Taverns quoted cool clique (3)