I pinch change to add to the kitty (4,2)
I believe the answer is:
chip in
'add to the kitty' is the definition.
(I've seen this before)
'i pinch change' is the wordplay.
'change' indicates anagramming the letters.
'i'+'pinch'='ipinch'
'ipinch' with letters rearranged gives 'CHIP-IN'.
'to' is the link.
(Other definitions for chip in that I've seen before include "Make a contribution" , "hole the ball" , "I pinch (anag)" , "Pay part of the cost of something" , "add to the kitty" .)