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.