Remove stems from spinach; wash leaves thoroughly, pat dry. Set aside.
In a large Dutch oven, melt butter or margarine over medium heat. Add onion and cook, stirring frequently, until tender. Add flour and curry powder, stirring until smooth. Cook 3 minutes, stirring constantly. Gradually add broth, stirring until blended.
Add potato, carrots, celery, parsley, and sage; bring to a boil over medium-high heat, stirring frequently. Cook, stirring constantly, until mixture thickens slightly. Cover, reduce heat, and simmer 15 minutes.
Stir in spinach, turkey, half and half, salt, and pepper; cover and simmer 10 minutes, stirring occasionally. Adjust spices to taste before serving.