Group around bar suffering reversal in game (6)
I believe the answer is:
tennis
'game' is the definition.
(tennis is a game)
'group around bar suffering reversal' is the wordplay.
'group' becomes 'set' (both can mean a collection).
'around' means one lot of letters goes inside another.
'bar' becomes 'inn' (both can mean a drinking establishment).
'suffering reversal' says the letters should be written in reverse.
'set' going around 'inn' is 'sinnet'.
'sinnet' backwards is 'TENNIS'.
'in' is the link.
(Other definitions for tennis that I've seen before include "Popular racket game - anyone for it?" , "Medieval, originally French, sport, codified by the British" , "Henman's game" , "Racket-and-ball game" , "Sport Dwight Davis gave trophy for" .)