Charge nothing to feed youth (4)
I believe the answer is:
load
'charge' is the definition.
(loading is a kind of charging)
'nothing to feed youth' is the wordplay.
'nothing' becomes 'O' (looks like zero - 0).
'to feed' is an insertion indicator (inserted letters are fed into the word).
'youth' becomes 'lad' (lad means a young man).
'o' inserted into 'lad' is 'LOAD'.
(Other definitions for load that I've seen before include "A heavy burden" , "pack" , "Weigh down" , "Burden, onus" , "Amount" .)