Such a villain is clearly roguish (4)

I believe the answer is:

arch

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'roguish' is the definition.
(I've seen this before)

I don't understand how the remainder of the clue works.

(Other definitions for arch that I've seen before include "one under a foot?" , "(archaic)" , "Curve of a bridge" , "Clever" , "Teasing; part of foot" .)

I've seen this clue in the Evening Standard.

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