Cunning, guileful (4)
I believe the answer is:
wily
I believe this is a double definition.
'cunning' is the first definition.
(synonyms)
'guileful' is the second definition.
(I know that guileful can be written as wily)
(Other definitions for wily that I've seen before include "Shrewd" , "Deceptively clever" , "Fly" , "Cunning; foxy" , "Skilled at gaining an advantage by deceit" .)