Possible Clues:

• Man, ace in performance, circus entertainer
• Current Borat-styled entertainer
• Big-top performer
• User of five ac
• Big top performer
• 'The United States considered it necessary to send a dignitary of that -- across the ocean' (Mark Twain)
• See 30-Across
• Bill joins Bill or retired performer
• Trapeze performer, e.g.
• Spends a lot of time hanging about looking over The Ring