Men could be hot wearing hats (5)
I believe the answer is:
chaps
'men' is the definition.
(chap can mean a man)
'hot wearing hats' is the wordplay.
'hot' becomes 'h' (abbreviation, eg on taps).
'wearing' is an insertion indicator.
'hats' becomes 'caps' (cap is a type of hat).
'h' put inside 'caps' is 'CHAPS'.
'could be' is the link.
(Other definitions for chaps that I've seen before include "Cowboy leggings" , "Blokes" , "People" , "Guy's" , "Cowboy's trousers; men" .)