The banquet of wine; so it is called, to note that it was not designed for a feast to fill their bellies, but rather for a banquet to delight and please their palates with wine and other delicacies: See Poole on "Esther 5:8".
Related Commentaries of Esther 7:2
Esther 7:2
2 And the king said again unto Esther on the second day at the banquet of wine, What is thy petition, queen Esther? and it shall be granted thee: and what is thy request? and it shall be performed, even to the half of the kingdom.