Playfully roguish (4)
I believe the answer is:
arch
'playfully roguish' is the definition.
(I've seen this in another clue)
This is the entire clue.
(Other definitions for arch that I've seen before include "part of fingerprint" , "Curved overhead structure" , "Curve that spans an opening" , "Vaulted opening" , "Playfully superior" .)