Gourmet: 'Good, great' (11)
I believe the answer is:
gastronomic
'gourmet' is the definition.
(top food)
'good great' is the wordplay.
'good' becomes 'g' (abbreviation).
'great' becomes 'astronomic' (very big).
'g'+'astronomic'='GASTRONOMIC'
(Other definitions for gastronomic that I've seen before include "Relating to fine food" , "Relating to good eating" , "Relating to fine eating" , "Relating to the art of good food" , "epicurean" .)