Curved part of a foot (4)
I believe the answer is:
arch
'curved part of a foot' 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 "Affectedly playful (4)" , "Roguish - chief - supporter" , "Affectedly playful like senior angel" , "This could be Wellington" , "Cunning; playful" .)