Justin Bieber, Lady Gaga and The Weeknd are their clients; Nobu and Osteria Mozza their clubhouses. Meet the driven young players shaping — and disrupting — the music industry. The honorees on the annual 40 Under 40 Power Players list were chosen by Billboard editors from more than 500 nominations submitted to Billboard.biz. Executives were judged on business impact, audience, market share and the chart and/or touring performance of clients during the past 12 months, as measured by Nielsen Music and Billboard Boxscore.LEE ANDERSON, 34Vp East Coast/agent, AM OnlyAnderson books some of the biggest stars in electronic music — make that “some of the biggest stars in music, period,” clarifies the Connecticut-raised resident of Brooklyn. Among the clients of this former promoter are Skrillex, Zedd, Disclosure, SBTRKT, Rudimental, Steve Angello and Claude VonStroke. Three years after AM Only forged a partnership with Paradigm Talent, the smaller agency still has an “independent spirit, something I really like.”If I Wasn’t in the Music Business: “I’d be in lifestyle marketing. I’m fascinated with human behavior, especially trends and consumer buying habits.”JEFFREY AZOFF, 29Agent, Creative Artists Agency+BRIAN MANNING, 38Agent, Creative Artists AgencyAzoff, bearing arguably the most formidable surname in the music business, books one…