Possible Clues:

• Barclays Center event
• Sport — willing — lame
• Lame ducks, maybe
• Mitchell's "The Circle ______"
• Plucky for part of the tennis match?
• Willing to be part of the match
• Ready and willing for tennis?
• Monopoly or marbles, for example
• Age about a thousand but sportive
• Eager and willing to accept challenge