Horse's foot part (7)
I believe the answer is:
pastern
'horse's foot part' is the definition.
(I know that pastern is part of horse\\u0027s foot)
This is all the clue.
(Other definitions for pastern that I've seen before include "'The knee of an horse' (Johnson)" , "Word Johnson misdefined" , "Part of horse's foot" , "Fetter-bone of horse" , "Wrongly-defined part of horse" .)