Least extensive (8)
I believe the answer is:
shortest
<span class="explanation-format__ClueExplanation">'<span class="explanation-format__original">least extensive</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 shortest that I've seen before include "She trots (anag.)" , "Least in length" , "most direct" , "'The longest way round is the ... way home' (proverb)" , "Most vertically challenged" .)