Part of a foot
I believe the answer is:
inch
<span class="explanation-format__ClueExplanation">'<span class="explanation-format__original">part of a foot</span>' is the definition.<br/ ><span class="explanation-format__explanation">(I know this)</span><br/ ><br/ >This is all the clue.<br/ ></span>
(Other definitions for inch that I've seen before include "Subdivision of 14 down" , "Edge slowly" , "Linear measure" , "Measure - small island - move slowly" , "Move by slow degrees" .)