Scrap the second group picked up (3-2)
I believe the answer is:
set-to
'scrap' is the definition.
(I know that set-to is a type of scrap)
I can't explain the rest of the clue.
(Other definitions for set-to that I've seen before include "brush with violence?" , "Ready - fight" , "Disagreement, fight" , "Brief fight" , "Fight, argument" .)