The ankle-bone (5)
I believe the answer is:
talus
I believe this clue is a double definition.
'the ankle' is the first definition.
(I've seen this in another clue)
'bone' is the second definition.
(I know that talus is a type of bone)
(Other definitions for talus that I've seen before include "Ankle-bone" , "Ankle bone" , "Yarns" , "Foot's part" .)