Not equilateral or isosceles (7)
I believe the answer is:
scalene
<span class="explanation-format__ClueExplanation">'<span class="explanation-format__original">not equilateral or isosceles</span>' is the definition.<br/ ><span class="explanation-format__explanation">(I've seen this in another clue)</span><br/ ><br/ >This is all the clue.<br/ ></span>
(Other definitions for scalene that I've seen before include "Having no sides for a match" , "(Of triangle) with no sides equal" , "not having evenly matched sides" , "(Of triangle) with each side of a different length" , "Describing a triangle with unequal sides" .)