It could enlarge bags of spice emptied in buffet (6)
I believe the answer is:
gusset
'it could enlarge bags' is the definition.
(piece of material used to enlarge a bag)
'spice emptied in buffet' is the wordplay.
'emptied' means to remove the middle letters.
'in' means one lot of letters goes inside another.
'buffet' becomes 'gust' (buffet can mean a gust of wind).
'spice' with its middle taken out is 'se'.
'se' put inside 'gust' is 'GUSSET'.
'of' is the link.
(Other definitions for gusset that I've seen before include "Guests (anag.)" , "Angular insertion in a garment" , "Strengthening material in a garment" , "Strengthening insert in garment" , "Strengthening piece of fabric" .)