Charges youngsters nothing to go in (5)
I believe the answer is:
loads
'charges' is the definition.
(I know this)
'youngsters nothing to go in' is the wordplay.
'youngsters' becomes 'lads' (I've seen this before).
'nothing' becomes 'O' (O resembles 0).
'to go in' means one lot of letters goes inside another.
'lads' going around 'o' is 'LOADS'.
(Other definitions for loads that I've seen before include "Burdens, cargoes" , "Tons, oodles" , "very much" , "Plenty (informal)" , "Charges; plenty" .)