Brave man to vex social worker (7)
I believe the answer is:
gallant
'brave man' is the definition.
'vex social worker' is the wordplay.
'vex' becomes 'gall' (both can mean to irritate).
'social worker' becomes 'ant' (ants are social insects).
'gall'+'ant'='GALLANT'
'to' acts as a link.
(Other definitions for gallant that I've seen before include "Brave and honourable" , "Valiant; courteous" , "Brave; courteous" , "Dashing, debonair young man" , "Amorous" .)