Breaking a creed to sin leads to defilement (11)
I believe the answer is:
desecration
'defilement' is the definition.
(thesaurus)
'breaking a creed to sin leads' is the wordplay.
'breaking' is an anagram indicator.
'leads' says to put letters next to each other (some letters go in front of others).
'creed'+'to'+'sin'='creedtosin'
'a' put after 'creedtosin' is 'creedtosina'.
'creedtosina' with letters rearranged gives 'DESECRATION'.
'to' acts as a link.
(Other definitions for desecration that I've seen before include "Violent disrepect" , "doing harm to something sacred" , "Damage of anything sacred" , "Violating" , "Violently disrespectful treatment" .)