The steely chic of DKNY's man this season spoke volumes about life for Donna's young' uns in New York Citythey now want to look like they mean business. Hence, the parade of charcoal-toned twills, tweeds, and flannels that defined her menswear for fall. Mind you, there were allowances made for the fact that the modern Wall Streeter isn't as buttoned-up-tight as his predecessors. Though trousers were slim, the tailoring wasn't strict: Jackets were shorter, slightly boxy in their construction, and easy-shouldered. Everything was worn with boots. And the narrow silk ties that invariably accompanied the collection's shirts had a muted flash, which complemented the paillettes and Lurex of the womenswear. Even the more casual items felt dressy, like the nylon taffeta blouson, the cabled cardigan jacket, and the steel-gray snorkel parka. Clearly, there is no excuse to look sloppy on the new frontiers of finance.