Seen in Benares, a richly decorated garment (4)
I believe the answer is:
sari
'garment' is the definition.
(sari is a kind of garment)
'seen in benares a richly decorated' is the wordplay.
'seen in' indicates a hidden word.
'SARI' is hidden in the letters of 'benares a richly decorated'.
(Other definitions for sari that I've seen before include "Hindu woman's dress" , "Indian costume" , "Asian dress" , "Hindu female garment" , "Traditional Indian women's dress" .)