Close-fitting jackets on very soon? (7)
I believe the answer is:
tonight
'very soon?' is the definition.
'close-fitting jackets on' is the wordplay.
'close-fitting' becomes 'tight' (similar in meaning).
'jackets' means one lot of letters goes inside another.
'tight' enclosing 'on' is 'TONIGHT'.
(Other definitions for tonight that I've seen before include "West Side Story number" , "Got thin (anag)" , "Selection from West Side Story" , "Later this evening" , "next retirement occasion" .)