Fellow hot: better taken outside (4)
I believe the answer is:
chap
'fellow' is the definition.
(both can mean a man)
'hot better taken outside' is the wordplay.
'hot' becomes 'h' (abbreviation eg on taps).
'better' becomes 'cap' (both can mean to beat somebody else's attempt).
'taken outside' is an insertion indicator.
'h' going within 'cap' is 'CHAP'.
(Other definitions for chap that I've seen before include "Sore; cheek; man" , "Raw, cracked patch on skin" , "Become sore; fellow" , "Skin crack due to cold - bloke" , "Man, boy, fellow" .)