All the rage (6)
I believe the answer is:
trendy
<span class="explanation-format__ClueExplanation">'<span class="explanation-format__original">all the rage</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 trendy that I've seen before include "following fashion" , "Smart" , "In accordance with the latest fad" , "following latest convention" , "Modish" .)