Sherried Cider Giblet Gravy

1 cup dry Sherry
1 cup apple cider (preferably sparkling)
6 tablespoons all-purpose flour
2 cups turkey giblet stock or chicken broth plus additional stock or broth for thinning gravy

Skim fat from pan juices, reserving 1/4 cup fat
On top of stove deglaze pan with Sherry over moderately high heat, scraping up brown bits.
Stir in cider.
Bring Sherry mixture to a boil and remove pan from heat.