Plenty of boys retaining nothing (5)
I believe the answer is:
loads
'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' indicates putting letters inside (inserted letters are held or retained).
'nothing' becomes 'O' (looks like zero - 0).
'lads' placed around '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" .)