Being virtuous is not commonly involved in being devious (7)
I believe the answer is:
saintly
'being virtuous' is the definition.
(thesaurus)
'not commonly involved in being devious' is the wordplay.
'not commonly' becomes 'ain't' (non-standard version of 'isn't' or 'aren't').
'involved in' is an insertion indicator.
'being devious' becomes 'sly' (I've seen this before).
'aint' put into 'sly' is 'SAINTLY'.
'is' is the link.
(Other definitions for saintly that I've seen before include "Very virtuous" , "good!" , "Beatific" , "Very holy" .)