Concision; shortness (7)
I believe the answer is:
brevity
<span class="explanation-format__ClueExplanation">This clue is a double definition.<br/ ><br/ >'<span class="explanation-format__original">concision</span>' is the first definition.<br/ ><span class="explanation-format__explanation">(I've seen this before)</span><br/ ><br/ >'<span class="explanation-format__original">shortness</span>' is the second definition.<br/ ><span class="explanation-format__explanation">(I've seen this in another clue)</span><br/ ><br/ ></span>
(Other definitions for brevity that I've seen before include "The soul of wit?" , "Succinctness" , "economy ..." , "Terseness" , "considered the essence of wit" .)