graduation garb (5)
(Other definitions for robes that I've seen before include "Ceremonial clothing" , "Gowns" , "trappings of office?" , "Official vestments" , "Sober (anag)" .)
(Other definitions for robe that I've seen before include "judge's garment" , "habit" , "Long loose garment or dressing gown" , "Dressed buffalo hide" , "Old cloak for Boer" .)