Fellow hot wearing beret (4)
I believe the answer is:
chap
'fellow' is the definition.
(both can mean a man)
'hot wearing beret' is the wordplay.
'hot' becomes 'h' (abbreviation eg on taps).
'wearing' is an insertion indicator.
'beret' becomes 'cap' (beret is a type of cap).
'h' put inside 'cap' is 'CHAP'.
(Other definitions for chap that I've seen before include "we prefer not to have on hand" , "Fellow; sore skin area" , "Cracked patch (of skin) - gentleman" , "Bloke, fellow" , "Raw, cracked patch on skin" .)