Ceremonial dress (4)
I believe the answer is:
robe
<span class="explanation-format__ClueExplanation">'<span class="explanation-format__original">ceremonial dress</span>' is the definition.<br/ ><br/ >This is the entire clue.<br/ ></span>
(Other definitions for robe that I've seen before include "Gown or dress of office" , "Dressing-gown" , "official dress" , "habit" , "Loose outer garment" .)