Task: Question Answering
Input (English): Passage: A musician named Dixie Dwyer begins working with mobsters to advance his career but falls in love with the girlfriend of gangland kingpin Dutch Schultz.
A dancer from Dixie's neighborhood, Sandman Williams, is hired with his brother by the Cotton Club, a jazz club where most of the performers are black and the customers white. Owney Madden, a mobster, owns the club and runs it with his right-hand man, Frenchy.
Dixie becomes a Hollywood film star, thanks to the help of Madden and the mob but angering Schultz. He also continues to see Schultz's moll, Vera Cicero, whose new nightclub has been financed by the jealous gangster.
In the meantime, Dixie's ambitious younger brother Vincent becomes a gangster in Schultz's mob and eventually a public enemy, holding Frenchy as a hostage.
Sandman alienates his brother Clay at the Cotton Club by agreeing to perform a solo number there. While the club's management interferes with Sandman's romantic interest in Lila, a singer, its cruel treatment of the performers leads to an intervention by Harlem criminal "Bumpy" Rhodes on their behalf.
Dutch Schultz is violently dealt with by Madden's men while Dixie and Sandman perform on the Cotton Club's stage. 
Question: How does the dancer know Clay?
Output (English): his brother.