Long loose-fitting robe (6)
I believe the answer is:
caftan
'long loose-fitting robe' is the definition.
(I've seen this before)
This is all the clue.
(Other definitions for caftan that I've seen before include "Long cloak-like garment with sleeves" , "Type of long dress with wide sleeves" , "Turkish loose garment" , "Middle-Eastern long dress" , "Cotton or silk ankle-length garment with full sleeves worn by men in the Levant" .)