Conniving (7)
(Other definitions for devious that I've seen before include "Not straightforward, underhand" , "Not straightforward or direct" , "Going astray" , "Machiavellian, roundabout" , "Tricky or shifty" .)
'conniving' is the definition.
(thesaurus)
This is the entire clue.
(Other definitions for shifty that I've seen before include "'Evasive, devious (6)'" , "Unreliable" , "Devious - wily" , "Sneaky and sly" , "Furtive" .)