This is a first to be stuck on this one - Kayakamina, Lie-in-King et al assistance please! 7ac (6) Imaginary idyll?A?A?? and 3d(4,2,7) unexpected problem solver D??? E? M?C?I?A ( I thought perhaps et machina but no exression springs to mind)
3d: deus ex machina (a literary ploy to resolve difficult plot developments)
7a: Xanadu (Coleridge's opium-inspired poem of Kubla Khan's summer palace)