Related Clues:

• Tic-tac-toe line-up, perhaps
• Marks a ballot
•     Deletes, with 'out'
• Strikes through
• Marks (out)
• Frame fillers in a perfect bowling game
• Illiterates' signatures
• Marks a ballot
• Signs quickly
• Crosses out
• Some signatures
• Crosses off, in a way
• Checks off
• Tic-tac-toe side
• ''Hollywood Squares'' symbols