Time span (8)
I believe the answer is:
duration
<span class="explanation-format__ClueExplanation">'<span class="explanation-format__original">time span</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 duration that I've seen before include "Time scale" , "Length of time" , "Term, span, time" , "Period during which something continues" , "Around it (anag.)" .)