A quarrel about petty point (4)
I believe the answer is:
spat
'a quarrel about petty point' is the definition.
(I've seen this before)
This is all the clue.
(Other definitions for spat that I've seen before include "Trivial quarrel" , "Pat's involved in petty quarrel" , "Gestured with contempt" , "Petty quarrel - gaiter" , "Slight argument" .)