Picaroon stops craving lucre, which is forgivable (6)
I believe the answer is:
venial
'is forgivable' is the definition.
(synonyms)
'picaroon stops craving lucre' is the wordplay.
'picaroon' becomes 'I' (where the crossword setter is 'Picaroon').
'stops' means one lot of letters goes inside another.
'craving lucre' becomes 'venal' (desiring money).
'i' put into 'venal' is 'VENIAL'.
'which' is the link.
(Other definitions for venial that I've seen before include "Not serious, like small sin" , "An evil (anag) - easily excused" , "Easily forgiven, a sin say" , "Of sin, pardonable, not too serious" , "Excusable" .)