Live wildly in sin (4)
I believe the answer is:
evil
'sin' is the definition.
(thesaurus)
'live wildly' is the wordplay.
'wildly' indicates anagramming the letters.
'live' with letters rearranged gives 'EVIL'.
'in' acts as a link.
(Other definitions for evil that I've seen before include "Profoundly malevolent" , "A live sort of badness" , "Villainy" , "source of harm" , "Immorality" .)