Accepted a deadly sin (6)
I believe the answer is:
agreed
'accepted' is the definition.
(agreeing is a kind of accepting)
'a deadly sin' is the wordplay.
'deadly sin' becomes 'greed' (greed is a kind of deadly sin).
'a'+'greed'='AGREED'
(Other definitions for agreed that I've seen before include "Accepted; tallied" , "Assented, acquiesced" , "Concurred - tallied" , "Mutually settled" , "OK, fine!" .)