Truth alternative, in a game (4)
I believe the answer is:
dare
'truth alternative in a game' is the definition.
(I've seen this in another clue)
This is the entire clue.
(Other definitions for dare that I've seen before include "Have the courage to try something" , "Challenge, defy, face" , "Throw down the gauntlet" , "Risk; challenge" , "Take a chance - read about it" .)