civic leaders: leaders of a city
sport figures filling the hotel ballroom: That the sports figures are entering the room bit by bit and that it starts to get crowded.
They: "they" is indeed refering to whom
Fund-raiser: somebody who raises the fund Somebody who has the intention to raise a certain amount of money or goods to support an organisation/ it's for a good cause.
banquet's featured entertainer: the banquet is the thing that takes place in the ballroom, it's the gadering including all the special guests. A banquet also means a big dinner party. So, in a nutshell; Lots of VIPS and lots of food and champagne
featured entertainer: That you were the official entertainer.
Student or Learner