Artfully subtle (3)
I believe the answer is:
sly
'artfully subtle' is the definition.
(I've seen this in another clue)
This is the entire clue.
(Other definitions for sly that I've seen before include "Wily, shifty" , "Cunning, foxy" , "Devious, cunning" , "Crafty, devious" , "Unpleasantly cunning and secretive" .)