Fellow getting hot in headgear? (4)
I believe the answer is:
chap
'fellow' is the definition.
(both can mean a man)
'hot in headgear?' is the wordplay.
'hot' becomes 'h' (abbreviation eg on taps).
'in' is an insertion indicator.
'headgear?' becomes 'cap' (cap is a kind of headgear).
'h' put within 'cap' is 'CHAP'.
'getting' acts as a link.
(Other definitions for chap that I've seen before include "Split in skin" , "Fellow < makes > crack" , "Become sore; fellow" , "Fish" , "Raw, cracked patch on skin" .)