Ball dress (4)
I believe the answer is:
gown
<span class="explanation-format__ClueExplanation">'<span class="explanation-format__original">ball dress</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 gown that I've seen before include "Elegant dress" , "Academic robe" , "Dress for formal occasions" , "Loose dress or robe" , "Ball dress" .)