Charges the boys nothing to enter (5)
I believe the answer is:
loads
'charges' is the definition.
('load' can be a synonym of 'charge')
'the boys nothing to enter' is the wordplay.
'the boys' becomes 'lads' (lad is a kind of boy).
'nothing' becomes 'o' (looks like zero - 0).
'to enter' means one lot of letters goes inside another.
'lads' placed around 'o' is 'LOADS'.
(Other definitions for loads that I've seen before include "bags" , "great deal" , "Puts on weight" , "in quantity" , "Plenty (informal)" .)