Slight quarrel (4)
I believe the answer is:
spat
'slight quarrel' is the definition.
(I've seen this before)
This is all the clue.
(Other definitions for spat that I've seen before include "Ejected saliva from the mouth" , "Unimportant quarrel between Pats" , "Trivial quarrel" , "Petty quarrel - gaiter" , "Spoke violently" .)