Gourmet’s colossal waste ending in bin (9)
I believe the answer is:
epicurean
'gourmet's' is the definition.
(synonyms)
'colossal waste ending in bin' is the wordplay.
'colossal' becomes 'epic' (epic can mean grand or colossal).
'waste' becomes 'urea' (compound in urine).
'ending in' suggests the final letters.
The final letter of 'bin' is 'n'.
'epic'+'urea'+'n'='EPICUREAN'
(Other definitions for epicurean that I've seen before include "Gourmet" , "immoderate character" , "follower of luxury" , "enjoyer of fine food" , "Hedonist" .)