gusset. 'it could enlarge bags' is the definition. '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'.. "/>