Very good! (informal) (5)
(Other definitions for magic that I've seen before include "Art that supposedly invokes supernatural powers" , "Enchanting quality" , "Unexpectedly produce" , "Sorcery - conjuring" , "'Charms, spells, illusions (5)'" .)
(Other definitions for great that I've seen before include "Storage container" , "The Plough" , "Of major significance - very good" , "Extensive; excellent" , "Very large in size, quantity, etc." .)