Small piece; fight (5)
I believe the answer is:
scrap
I believe this is a double definition.
'small piece' is the first definition.
(I've seen this in another clue)
'fight' is the second definition.
(a scrap is a minor fight)
(Other definitions for scrap that I've seen before include "row" , "Discard; fight" , "Just a fragment, maybe of food" , "Turn into refuse" , "Fragment or slang fight (5)" .)