Game that's good set in stone (5)
I believe the answer is:
rugby
'game' is the definition.
(rugby is a sport or game)
'good set in stone' is the wordplay.
'good' becomes 'g' (abbreviation).
'set in' is an insertion indicator.
'stone' becomes 'ruby' (I've seen this in other clues).
'g' put inside 'ruby' is 'RUGBY'.
'that's' acts as a link.
(Other definitions for rugby that I've seen before include "Sport with oval ball" , "Public school founded in 1567" , "Team game" , "Type of football; school" , "Ball-game" .)