Establish before start - everything is a game (8)
I believe the answer is:
baseball
'game' is the definition.
(baseball is a kind of game)
'establish before start everything' is the wordplay.
'establish' becomes 'base' (synonyms).
'start' suggests taking the first letters.
'everything' becomes 'all' (all things).
The initial letter of 'before' is 'b'.
'base'+'b'+'all'='BASEBALL'
'is a' is the link.
(Other definitions for baseball that I've seen before include "Slab able to be used in the game?" , "Game played badly in the sable lab" , "Nine-a-side game" , "American game like rounders" , "Bale labs out for this game" .)