Related Clues:
- An X could represent it
- Little jerk
- Peculiarity
- Automatic, as a reaction
- Involuntary muscular contraction
- Game opener?
- First X
- Uncontrolled contraction
- Foible
- First of three in a pencil/paper game
- It could be represented by an "X"
- Physiological reaction
- Persistent personal quirk
- ___-tac-toe
- First O?