Bones of the ankle and heel (6)
I believe the answer is:
tarsus
'bones of the ankle and heel' is the definition.
(I've seen this before)
This is the entire clue.
(Other definitions for tarsus that I've seen before include "biblical city" , "St Paul was born there" , "City of which St Paul was a native" , "ancient Turkish city" , "Part of the foot" .)