Bill Irwin and David Shiner will team up with Nellie McKay for a new clown show, “Old Hats,” to be directed by Tina Landau at Off Broadway’s Signature Theater.It’ll be the first collaboration from Irwin (“Who’s Afraid of Virginia Woolf?”) and Shiner since “Fool Moon,” which bowed on Broadway in 1993, hit the road and circled back to the Rialto for return runs in 1995 and 1998. Title won a special Tony in 1999. Singer-songwriter McKay, who had a Broadway thesping gig in the 2006 revival of “The Threepenny Opera,” also will appear in the show. Landau is currently repped Off Broadway with “A Civil War Christmas” at New York Theater Workshop. “Old Hats” will incorporate clowning, magic and tech into an evening of comic highjinks along the lines of “Fool Moon.” Show will be presented at the Signature as part of its Legacy program for writers whose work has previously been produced by the theater in a season-long showcase of their plays. Irwin was the company’s scribe in residence during the 2003-04 season. “Old Hats” begins previews Feb. 12 ahead of a March 4 opening at the org’s midtown venue.