Nancy takes advantage of work (7)
I believe the answer is:
milksop
'nancy' is the definition.
(thesaurus)
'takes advantage of work' is the wordplay.
'takes advantage of' becomes 'milks'.
'work' becomes 'op' (common abbreviation for 'opus').
'milks'+'op'='MILKSOP'
(Other definitions for milksop that I've seen before include "Feeble youth" , "Feeble and effete person" , "Cissy (informal) -- limps OK (anag)" , "Inefectual man" , "(Young) wimp" .)