A game decided by its one and only shot? (7,8)
I believe the answer is:
russian roulette
'a game' is the definition.
(I've seen this before)
'decided by its one and only shot?' is the wordplay.
I cannot really understand how this works, but
'one' could be 'an' (an apple is one apple) and 'an' is found within the answer.
This explanation may well be incorrect...
Can you help me to learn more?
(Other definitions for russian roulette that I've seen before include "suicidal undertaking" , "highrisk game" , "deadly stunt" , "Dangerous game of chance" , "risky business" .)