Part of horse's foot (4)
I believe the answer is:
hoof
<span class="explanation-format__ClueExplanation">'<span class="explanation-format__original">part of horse's foot</span>' is the definition.<br/ ><span class="explanation-format__explanation">(I've seen this before)</span><br/ ><br/ >This is all the clue.<br/ ></span>
(Other definitions for hoof that I've seen before include "Animal foot" , "Part of animal's foot" , "Ungulate's foot" , "Horny cover of foot" , "Part of horse's foot" .)