Start a fight (3-2)
I believe the answer is:
set-to
I believe this clue is a double definition.
'start' is the first definition.
(I've seen this before)
'a fight' is the second definition.
(I know that set-to is a type of fight)
(Other definitions for set-to that I've seen before include "Scrap" , "Altercation" , "Brief fight" , "brush with violence?" , "Disagreement, fight" .)