Adopt a defensive stance as traditionalist away (6,3)
I believe the answer is:
square off
'adopt a defensive stance' is the definition.
(to square off is to stand as if about to fight)
'traditionalist away' is the wordplay.
'traditionalist' becomes 'square' (both can mean a boring or traditionalist person).
'away' becomes 'off' (synonyms).
'square'+'off'='SQUARE OFF'
'as' is the link.
(Other definitions for square off that I've seen before include "Raise dukes" , "prepare for fight" , "What boxer might do if attacked" .)