Not trendy (5)
I believe the answer is:
unhip
<span class="explanation-format__ClueExplanation">'<span class="explanation-format__original">not trendy</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 unhip that I've seen before include "square" , "Not cool" , "uncool" .)