Possible Clues:

• *Gambler's stoic expression
• Impassive expression that hides one's true feelings
• Impassive expression
• One making a stir has to deal with blank look
• Inscrutable expression assumed to conceal emotion
• Inscrutable person
• Emotionless look
• Feature of some bluffs
• You'll get nothing out of a good one
• Impassive expression (at the card table?)