R&B singer Amy Winehouse kept it gangsta at the Glastonbury music festival Saturday. After taking the stage, the troubled “Rehab” singer climbed down into the pit and scuffled briefly with a event-goer. It was unclear what sparked the altercation but witnesses say the fan tried to grab Winehouse. Winehouse sang for about an hour in front of an estimated crowd of 80,000. Despite the scuffle, Winehouse was reportedly in fine voice as she performed songs from her Grammy-winning album Back to Black, including “Rehab” and “You Know I’m No Good.” The performance came just after she was hospitalized. Her father says she developed emphysema from smoking cigarettes and crack cocaine, although her spokeswoman has said she only has pre-emphysema symptoms. See Video of Mini Scuffle: