Related Clues:

• First X, maybe
• Muscle spasm
• Sudden contraction
• Center X or O
• Sign of nerves
• Muscle contraction
• Middle X of X-X-X
• It's 'twixt tic and toe
• Involuntary twitch
• Tie ___
• One-third of a simple game
• Recurrent twitch
• Eccentricity
• An X could represent it
• Tic-toe filler