How can i book a celebrity for an event at my restaurant/club ?

In general, when booking a celebrity for an event, all negotiations are handled by their agent. If they do not have one, the next best person will be their manager.
Before establishing contact, you need to know the following: the venue, budget, the date of your event, what you expect celebrity to do at your event (i.e. perform, speak), who's funding the event (i.e. sponsors), public or private event, celebrity confirmation deadline, and arrangements you are willing to cover (i.e. transportations, accommodations).