Possible Clues:

• Russell rings American city on needing singular fellow
• 'Who wants to volunteer?'
• Memorable repeated question by the economics teacher (played by Ben Stein) in "Ferris Bueller's Day Off"
• 'Is -- out there?'
• 'Doesn't matter who'
• Animal-hunting trip
• Some singular person from New York?
• 'Who'd like to volunteer?'
• Whoever is over there, a north European hosts
• See 21-Down