The story
From red + cartel. "Red" refers to the team colors of Arsenal F.C., Manchester United F.C., and Liverpool F.C.
Etymology from Wiktionary, CC BY-SA 4.0.
Red Cartel
Today it means: An alleged conspiracy between British football clubs Arsenal, Manchester United, and Liverpool to use their influence in the Premier League to manipulate league financial regulations to undermine challengers. Full definition →