Like a nun, possibly, knowing about revised rites (8)
I believe the answer is:
sisterly
'like a nun' is the definition.
(some nuns are called sister)
'knowing about revised rites' is the wordplay.
'knowing' becomes 'sly' (sly can mean crafty or knowing).
'about' indicates putting letters inside.
'revised' indicates an anagram.
'rites' anagrammed gives 'ister'.
'sly' going around 'ister' is 'SISTERLY'.
'possibly' acts as a link.
(Other definitions for sisterly that I've seen before include "Reportedly none" , "I try less (anag.)" , "To do with one's female sibling" , "relatively close" , "Friendly in a female way" .)