Gourmand's grand time in town (7)
I believe the answer is:
glutton
'gourmand's' is the definition.
(synonyms)
'grand time in town' is the wordplay.
'grand' becomes 'g' (G is short for grand as in a thousand).
'time' becomes 't' (abbreviation).
'in' is an insertion indicator.
'town' becomes 'luton' (town in Bedfordshire).
't' inserted inside 'luton' is 'lutton'.
'g'+'lutton'='GLUTTON'
(Other definitions for glutton that I've seen before include "Big eater" , "One eats too much" , "Gourmand" , "Immoderate eater" , "Excessive eater; wolverine" .)