United tie incorporating upcoming game (8)
I believe the answer is:
together
'united' is the definition.
(thesaurus)
'tie incorporating upcoming game' is the wordplay.
'tie' becomes 'tether' (I've seen this before**).
'incorporating' means one lot of letters goes inside another.
'upcoming' is a reversal indicator.
'game' becomes 'go' (go is a kind of game).
'go' written backwards gives 'og'.
'tether' enclosing 'og' is 'TOGETHER'.
(Other definitions for together that I've seen before include "One with another, simultaneously" , "Appearing as a couple" , "Collected" , "Well-balanced" , "In company or in conjunction" .)