Gown of office (4)
I believe the answer is:
robe
'gown of office' is the definition.
(I've seen this in another clue)
This is the entire clue.
(Other definitions for robe that I've seen before include "Clerical garment" , "Loose garment for Boer" , "Long loose garment or dressing gown" , "Formal attire" , "Dressing-gown" .)