Saucy curve (4)

I believe the answer is:

arch

I believe this clue is a double definition.

'saucy' is the first definition.
(thesaurus)

'curve' is the second definition.
(arch is a kind of curve)

(Other definitions for arch that I've seen before include "This could be Wellington" , "Chief; bow" , "Consciously or affectedly playful - under a bridge?" , "Roguish, cunning" , "Curve of the foot" .)

I've seen this clue in The Telegraph.

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