Isaac Mizrahi on stage, style and the legacy of Unzipped: ‘Fashion has no real spine any more’

The designer defined the glory days of 90s style with a wit that made him every supermodel’s best friend. As he gears up for a new cabaret show, he’s as outspoken as ever There’s a lot to look at in Isaac Mizrahi’s studio in New York’s Greenwich Village: sketches, bulletin boards, fabrics, memorabilia, heaps of books, a Golden Girls puzzle set. But my eyes lock in on two dolls, Snoopy and his…