Three feet (4)
I believe the answer is:
yard
<span class="explanation-format__ClueExplanation">'<span class="explanation-format__original">three feet</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 yard that I've seen before include "Measure - enclosed paved area" , "Space outside" , "compound" , "Three feet U patio" , "American garden" .)