Preset oven to 450 degrees.
Remove the outer green rind and most of the pulp from the watermelon and cut the remaining rind into l/4-inch cubes before measuring.
Place the measured, cubed rind in a medium saucepan; add water to cover. Bring to a boil, then simmer until translucent and tender. Drain.
Add sugar, cinnamon, cloves, nutmeg, raisins, pecans, salt, flour, and vinegar to cubes. Stir well.
Pour the mixture into pastry shell; cover with top pastry crust and cut steam vents. Bake until crust is slightly browned.
Reduce temperature to 350 degrees and bake until filling is set.