Possible Clues:

• Numbers game?
• 9 x 9 game
• Taking flight from here to America, about to tackle a grid-filling problem
• Logic puzzle originally called 'Number Place'
• Type of puzzle whose name means 'single number'
• Puzzle with a 9 x 9 grid
• America backing party UK rejected? A puzzle
• Puzzle — UK's duo (anag)
• Political allies upset about party? That's a puzzle
• Party breaks up UK-US link; it's a puzzle