One of England's most gossiped-about young singers played her first show in the U.S. last week. We were there. So were Jay-Z, Mos Def, Mark Ronson, and a small crowd lucky enough to score a ticket to the gig at Joe's Pub, a cozy 160-seat club in Manhattan. In the U.K., Amy Winehouse is a pop star and tabloid regular due to her outrageous behavior, reported eating disorders, and performances where she appears to be very, very drunk. The bold-faced rappers didn't just come for spectacle, however. Winehouse's second album, Back to Black, is one of the most anticipated releases of the season (it hits U.S. stores March 13) thanks to the autobiographical single ''Rehab,'' in which she huskily declares, ''They tried to make me go to rehab/I said, no, no, no!'' Coming off like a trampy prom queen black cocktail dress, amaretto sour in hand, unstable beehive hairdo the 23-year-old Londoner juices up '60s-style girl-group soul with hip-hop swagger. And unlike a lot of today's vocal virtuosos, her swinging tunes about bad fellas (''Back to Black'') and heartache (''Tears Dry on Their Own'') feel authentically sorrowful. Sure, Winehouse keeps gossip columnists busy, but her New York coming-out proved she's much more than mere shtick.