Pinch for every youngster (6)
I believe the answer is:
nipper
'youngster' is the definition.
(I know that youngster can be written as nipper)
'pinch for every' is the wordplay.
'pinch' becomes 'nip' (nip can mean to pinch or bite).
'for every' becomes 'per' ('per' means 'for each' or 'for every').
'nip'+'per'='NIPPER'
(Other definitions for nipper that I've seen before include "Child (slang); one that 19s" , "Slang boy or lobster claw" , "Small child (informal)" , "Little boy" , "Child - ankle-biter?" .)