Holier-than-thou (13)
I believe the answer is:
sanctimonious
'holier-than-thou' is the definition.
(synonyms)
This is the entire clue.
(Other definitions for sanctimonious that I've seen before include "with a holier-than-thou attitude" , "Ostentatiously pious" , "Making show of being morally superior" , "Self-righteous" , "Canting" .)