Blasphemy (6)
'blasphemy' is the definition.
(I've seen this before)
This is the entire clue.
(Other definitions for heresy that I've seen before include "Opinion contrary to accepted religious beliefs" , "refusal to conform" , "Unorthodox religious opinion" , "Unorthodox doctrine" , "The wrong idea" .)
'blasphemy' is the definition.
(thesaurus)
This is all the clue.
(Other definitions for imprecation that I've seen before include "anathema" , "Bad language" , "Spoken curse" , "blast?" .)