Kelly Clarkson kicks off her residency at the Colosseum at Caesars Palace in Las Vegas on July 11. (Denise Truscello/Getty Images for Live Nation Las Vegas)Kelly Clarkson says she is postponing her Las Vegas residency so she can be with her children because their father, her ex-husband Brandon Blackstock, has been ill."Unfortunately, I need to postpone the remainder of the August Studio Session dates in Las Vegas," Clarkson announced in a post on Instagram.