Wideness (7)
I believe the answer is:
breadth
<span class="explanation-format__ClueExplanation">'<span class="explanation-format__original">wideness</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 breadth that I've seen before include "generosity of mind" , "Distance from side to side" , "Measure" , "Wide range" , "Width, thickness" .)