Other side about to need judge in game (9)
I believe the answer is:
blackjack
'game' is the definition.
(blackjack is a card game)
'other side about to need judge' is the wordplay.
'other side' becomes 'back' (the back of something).
'about' is an insertion indicator.
'to need' becomes 'lack' (to lack something is to be in need of it).
'judge' becomes 'j' (abbreviation for judge).
'lack'+'j'='lackj'
'back' enclosing 'lackj' is 'BLACKJACK'.
'in' acts as a link.
(Other definitions for blackjack that I've seen before include "Gambling card game" , "Casino card game" , "Vingt-et-un - pirates' ensign" , "2 8 [CASINO GAME]" , "A card game in which the object is to beat the bank" .)