Cunning head (4)
I believe the answer is:
arch
This clue is a double definition.
'cunning' is the first definition.
(I've seen this before)
'head' is the second definition.
('arch' can be a synonym of 'head')
(Other definitions for arch that I've seen before include "Coyly playful" , "Knowing, coy" , "Curved entrance" , "Main" , "Teasing; part of foot" .)