Dissolute parasites cast out sin (10)
I believe the answer is:
licentious
'dissolute' is the definition.
(thesaurus)
'parasites cast out sin' is the wordplay.
'parasites' becomes 'lice' (I've seen this before).
'cast' indicates an anagram (letters are dispersed or cast around).
'out'+'sin'='outsin'
'outsin' is an anagram of 'ntious'.
'lice'+'ntious'='LICENTIOUS'
(Other definitions for licentious that I've seen before include "Promiscuous" , "disregarding accepted rules" , "Depraved" , "Abandoned" .)