Rearranging the letters of 'Frosty the Snowman' (Song) gives:
A sworn soften myth.
(by Rodney Koodray Jr) (2007) (pending approval)
Other related anagrams without their own page:
"The frosty North Pole with food under igloos," -> "Foreshorten thy plot with delusion for good." (by Jim Banholzer) (2017) (pending approval)
"Frosty North Pole" -> "Pronto Hot Flyers." (by Jim Banholzer) (2015) (pending approval)
"The frosty north pole" -> "Foreshorten Thy Plot." (by Jim Banholzer) (2014) (pending approval)
"The Snowman, the classic tale by Raymond Briggs." -> "This says: so maybe cold can bring gentle warmth." (by Segura by hand) (2002)
"The North Pole" -> "Phenol hotter." (by Jim Banholzer) (2014) (pending approval)
"The North Pole" -> "Porthole then." (by Jim Banholzer) (2014) (pending approval)
"Mountain man supper, at a table replete with food." -> "Puma, Marten, fowl, bread, soup, pie; eat the lot at Inn." (by Jim Banholzer) (2017) (pending approval)