Expressionless visage (5,4)
![Ross](/clue/static/ross-mug.min.png)
I believe the answer is:
poker face
(Other definitions for poker face that I've seen before include "Inscrutable person" , "Impassive expression (at the card table?)" , "Expressionless visage, useful when playing cards" , "Countenance giving nothing away" , "Card player's deadpan expression" .)