Square footage (4)
I believe the answer is:
area
<span class="explanation-format__ClueExplanation">'<span class="explanation-format__original">square footage</span>' is the definition.<br/ ><span class="explanation-format__explanation">(I've seen this in another clue)</span><br/ ><br/ >This is the entire clue.<br/ ></span>
(Other definitions for area that I've seen before include "Space for a specific purpose, say picnic" , "The measure of a surface" , "Patch" , "District; plot" , "Territory" .)