One banqueting, not the first, in celebratory season (6)
I believe the answer is:
easter
'celebratory season' is the definition.
'one banqueting not the first' is the wordplay.
'one banqueting' becomes 'feaster'.
'not the first' means to remove the first letter.
'feaster' with its first letter taken off is 'EASTER'.
'in' is the link.
(Other definitions for easter that I've seen before include "Time to parade" , "8 9 [PACIFIC ISLAND]" , "Church festival" , "Christian festival of celebration" , "- Day; - bunny" .)