Preheat oven to 400 degrees F. Place rhubarb, apple slices, and raisins in bowl. Add lemon juice and spices. Allow to sit for 10 minutes. Then, add sugar and mix thoroughly. Add 1/4 cup flour and mix well. Ingredients make be a little juice, but that's okay. Add to pie shell.
In separate bowl, add 1/4 cup sugar and 1/2 cup flour. Mix well. Using a fork, cut in the 1/4 cup butter. Mix well; until crumbly. Add to top of pie mixture.
Bake in oven until crust is golden brown, about 1 hour. Serves with Cool Whip or ice cream. Enjoy.