Sort cranberries and discard stems and any bruised or decayed fruit. Rinse and drain berries. Peel pears; cut in half and core. In a 2- to 2 1/2-quart baking dish, combine cranberries, pears, and lemon slices.
In a 1- to 2-quart pan over medium-high heat, stir sugar, vinegar, ginger, cinnamon, cloves, and 1/2 cup water until mixture boils and sugar is dissolved. Pour over fruit. Cover dish tightly with foil.
Bake in a 350° regular or convection oven until pears are tender when pierced, 45 minutes to 1 hour. Serve warm or at room temperature.