Crab's claw (6)
(Other definitions for nipper that I've seen before include "Small boy - or crab?" , "Claw (large) - child (small)" , "Kid - claw" , "Crab - young shaver?" , "Child - ankle-biter?" .)
'crab's claw' is the definition.
(I've seen this before)
This is all the clue.
(Other definitions for pincer that I've seen before include "Surrounding (movement)" , "Front claw" , "Crab's nipper" , "Grasping limb of a crustacean" , "Crab's claw" .)