Throughout the film, Buster and his friends track down famous recluse Clay Calloway so that he'll be part of the show. It's pretty integral that Clay agrees to do it, and as luck would have it, he decides to join ... but not without some major convincing first.
You see, Clay's been away from the spotlight for so long due to the death of his wife, who was his muse for many years. After she dies, Clay doesn't see a reason to carry on since all of his songs are about her. It seems like he's ready to leave the past behind him once he agrees to do the show, but something interesting happens backstage.
Clay initially can't find the courage to walk out on stage. Instead, he hangs back with his guitar as Ash (Scarlett Johansson) goes out to sing in his place. There's a moment of contemplation. Will he make it out, or will he hang back? It's at this point a vision of his deceased wife appears, standing by his side. No, she's not actually standing there. It's a metaphor for how she'll always be there for him, and even though she may physically be gone, her spirit lives on in the music he wrote for her. By playing his songs, Clay ensures that her memory lives on.
