Squeeze sausages from casings into a 10- to 12-inch frying pan over high heat; add onion. With a spoon, break meat into fine chunks and stir often until meat is well browned, about 10 minutes.
Add grapes, 1/2 cup water, cloves, and cinnamon. Stir often until water is evaporated, 4 to 5 minutes. Add another 1/4 cup water and stir, mashing grapes if they don't pop, until liquid is evaporated and mixture is slightly thicker, about 8 minutes. Add pepper to taste.