Hindu festival (6)
I believe the answer is:
diwali
<span class="explanation-format__ClueExplanation">'<span class="explanation-format__original">hindu festival</span>' is the definition.<br/ ><span class="explanation-format__explanation">(I've seen this before)</span><br/ ><br/ >This is the entire clue.<br/ ></span>
(Other definitions for diwali that I've seen before include "Hindu festival; I'd wail (anag.)" , "Light festival" , "Hindu festival of lights" , "Indian festival" , "Festival in honour of Lakshmi" .)