A game faced impassively (5)
I believe the answer is:
poker
'a game' is the definition.
(poker is a kind of game)
I can't explain the rest of the clue.
Can you help me to learn more?
(Other definitions for poker that I've seen before include "One of many irons in the fire" , "declared to be stiff" , "Epitome of stiffness" , "Fire-iron" , "Fire prodder; game" .)