Milk? Fail to provide enough, nicking quarter of pint (4)
I believe the answer is:
skim
'milk?' is the definition.
(skim milk is a kind of milk)
'fail to provide enough nicking quarter of pint' is the wordplay.
I cannot really see how this works, but
'quarter' could be 's' and 's' is located in the answer.
The remaining letters 'kim' is a valid word which might be clued in a way I don't understand.
This may be the basis of the clue (or it may be nonsense).
(Other definitions for skim that I've seen before include "Remove top (of milk)" , "Pass swiftly and lightly over the surface" , "avoid paying income tax" , "Read hastily" , "Remove top layer; read bits of" .)