Set of ankle bones (6)
I believe the answer is:
tarsus
'set of ankle bones' is the definition.
(I've seen this in another clue)
This is all the clue.
(Other definitions for tarsus that I've seen before include "ancient Turkish city" , "Part of the foot" , "Bone" , "The seven bones of the upper foot and ankle" , "saint's birthplace" .)