Related Clues:

• Wash. State's Sea-___ Airport
• Middle X or O?
• 'Tic -- Dough'
• Certain X or O
• Half a mint?
• XXX part
• X-X-X part
• Center X?
• Middle O?
• XXX center
• Part of a "Hollywood Squares" winner
• Middle O of O-O-O
• Tie __
• Tic-__-toe
• Middle square, say