The phrase "underground fight club" refers to a secret group or organization where people engage in illegal or unregulated fights for entertainment or competition, often in hidden locations away from the public eye. Full definition
Literally, as it looks like Jason has spent the last decade in underground fight clubs. (laineygossip.com)
«Using all - new powers and abilities, Billie will infiltrate underground fight clubs and square off against the Sisters of the Oracular Order, the immortal Envisioned and the Outsider - obsessed Eyeless gang. (mammothgamers.com)
Far away from the stadiums full of lights, roaring audiences, and sponsored teams of the ever - growing eSports spectacle are enthusiasts gathering amongst themselves for underground fight clubs. (gamecritics.com)