Deviate before there's a fight, making a volte-face (9)
I believe the answer is:
turnabout
'a volte-face' is the definition.
(thesaurus)
'deviate before there's a fight' is the wordplay.
'deviate before' becomes 'turn' (I can't justify this - if you can you should give a lot more credence to this answer).
'there's' says to put letters next to each other.
'fight' becomes 'bout' (as in a bout in boxing).
'turn'+'a'+'bout'='TURNABOUT'
'making' acts as a link.
Can you help me to learn more?
(Other definitions for turnabout that I've seen before include "complete change of policy" , "change of heart" , "Total change of policy" , "That makes a change" .)