Organise a fight in a car (8)
I believe the answer is:
runabout
'a car' is the definition.
(runabout is a kind of car)
'organise a fight' is the wordplay.
'organise' becomes 'run' (I've seen this before**).
'fight' becomes 'bout' ('bout' can be a synonym of 'fight').
'run'+'a'+'bout'='RUNABOUT'
'in' is the link.
(Other definitions for runabout that I've seen before include "Vehicle for short trips" , "Small car used for short journeys" , "Small car for short trips" , "Small light vehicle" , "small aircraft" .)