In a small saucepan, off the heat, combine the wine, the juice from the lemon and orange, 1 of the squeezed orange quarters, the sugar, vanilla, cinnamon stick, and cloves. Add the pears and bring to a boil. Reduce heat and simmer, uncovered, turning the pears occasionally, until they're easily pierced with the tip of a knife, about 25 minutes. Using a slotted spoon, transfer the pears to individual plates. Remove and discard the orange quarter and spices. Return the liquid to a simmer and cook until syrupy and reduced by two-thirds, about 15 minutes, depending on size of pan. Spoon the sauce over the pears.
Tip Pears not quite ripe? Poaching in wine renders even firm fruit juicy and tender. For extra drama, serve this ruby red dessert with a scoop of vanilla ice cream.