Roguish, but of peculiar charm? (4)
I believe the answer is:
arch
'roguish' is the definition.
(I've seen this before)
'of peculiar charm?' is the wordplay.
'of' indicates the answer is hidden within the clue.
'ARCH' is hidden within 'peculiar charm'.
'but' acts as a link.
(Other definitions for arch that I've seen before include "Knowing, coy" , "Chief: crafty" , "Curved vault" , "Way though - on foot!" , "Affectedly playful (4)" .)