A gent may wear this belt and tie (4,4)
I believe the answer is:
cuff link
'a gent may wear this' is the definition.
(a formal gentleman might wear cufflinks)
'belt and tie' is the wordplay.
'belt' becomes 'cuff' (both can mean to hit).
'and' is a charade indicator (letters next to each other).
'tie' becomes 'link' (synonyms).
'cuff'+'link'='CUFF LINK'
(Other definitions for cuff link that I've seen before include "Decorative fastener" , "One of a pair of shirt sleeve fasteners" .)