Plenty of boys retaining nothing (5)
I believe the answer is:
'plenty' is the definition.
(I've seen this before)
'boys retaining nothing' is the wordplay.
'boys' becomes 'lads' (lad is a kind of boy).
'retaining' is an insertion indicator (inserted letters are held or retained).
'nothing' becomes 'o' (O resembles 0).
'lads' enclosing 'o' is 'LOADS'.
'of' is the link.
(Other definitions for loads that I've seen before include "A great many" , "in quantity" , "a lot" , "Masses; cargoes" , "great deal" .)