4d) English CEO dives into sea in relief (8)
13a) Tube essentially controlled by power underground in U.S. (6)
16d) It may be painful supporting clubs' climax to season. (3,5)
22a) Extremely like cars with a 15? (8)
24a) Weigh thoroughly - there's only a fraction in it (6)
Apology for no letters. All help much appreciated
Best thanks to all for responding to my plea for assistance so promptly. Apology for giving an incorrect clue for 22 across - thanks again michaelmph
'Best answer' an honourable draw between mac44 and Sipowicz.