Preheat the oven to 450°F (230°C).
Combine the ground beef, ground pork, onion, and water in a medium saucepan. Cover and cook over low heat, stirring occasionally, until the meat is fully cooked.
Meanwhile, place the potatoes in a small saucepan, cover with water, and boil until tender. Drain well.
Add the cooked potatoes, salt, allspice, cloves, and pepper to the meat mixture. Remove from the heat and mash until the filling is evenly combined but still has some texture.
Roll the pastry into two 11-inch circles on a lightly floured surface. Fit one circle into a 9-inch pie plate and spoon in the meat filling.
Cover with the remaining pastry. Seal and flute the edges, then cut several vents in the top crust.
Bake for about 20 minutes, until the crust is golden brown. Rest for 10 minutes before slicing.