About to fight wise man (6)
I believe the answer is:
caspar
'wise man' is the definition.
(I've seen this before)
'about to fight' is the wordplay.
'about' becomes 'ca' (short for circa).
'to fight' becomes 'spar' (sparring is a kind of fighting).
'ca'+'spar'='CASPAR'
(Other definitions for caspar that I've seen before include "One of the Magi" , "Wise man" , "Bearer of gift" .)