Dimension (11)
I believe the answer is:
measurement
<span class="explanation-format__ClueExplanation">'<span class="explanation-format__original">dimension</span>' is the definition.<br/ ><span class="explanation-format__explanation">(I've seen this before)</span><br/ ><br/ >This is the entire clue.<br/ ></span>
(Other definitions for measurement that I've seen before include "What a ruler may give" , "Dimension" , "Mensuration" , "Size" .)