Related Clues:

• Peculiarity
• Involuntary muscular contraction
• Game opener?
• Muscle malady
• First X
• Uncontrolled contraction
• Hiccup
• Contraction
• Foible
• First of three in a pencil/paper game
• It could be represented by an "X"
• Involuntary muscle contraction
• Muscle cramp
• Persistent personal quirk
• ___-tac-toe