Split after street fight (6)
I believe the answer is:
strive
'fight' is the definition.
(thesaurus)
'split after street' is the wordplay.
'split' becomes 'rive' ('rive' can be a synonym of 'split'**).
'after' says to put letters next to each other.
'street' becomes 'st'.
'rive' after 'st' is 'STRIVE'.
(Other definitions for strive that I've seen before include "Endeavour" , "Try hard, make an effort" , "Contend using rivets" , "Make every effort" , "Venture" .)