Sentence:  Epperlein and Tucker focus on two featherweight hopefuls: Dustin Poirier, a formidable contender who's looking to parlay a history of schoolyard violence and street-fighting into a potential career, and Albert Stainback, a more thoughtful yet more erratic and undisciplined fighter whose chief <WSD>gimmick</WSD> is entering the ring wearing a hat like the one Malcolm McDowell wore in "A Clockwork Orange". 
Meaning of the word marked with <WSD> tags:  A trick or device used to attain some end.