NB: everyone is following very good game (7)
I believe the answer is:
pinball
'game' is the definition.
(pinball is a kind of game)
'nb everyone is following very good' is the wordplay.
'everyone' becomes 'all' (I've seen this before).
'is following' says to put letters next to each other.
'very good' becomes 'pi' (I've seen this in other clues).
'nb'+'all'='nball'
'nball' put after 'pi' is 'PINBALL'.
(Other definitions for pinball that I've seen before include "Slot-machine game" , "Slot machine bagatelle" , "Electrically operated form of bagatelle" , "Game involving an enclosed table, played by operating flippers" , "Arcade game where a metal sphere negotiates hazards" .)