Place the orange and the washed apples, cut into quarters, into your slow cooker. Add the cinnamon, cloves, and syrup. Add enough water to cover the fruit.
Cook on low for 6-7 hours.
Once the fruit is very soft, mash it to release all the juices. Then let it cook for another hour.
Carefully strain the chunky liquid into a large pot or pitcher.
Store leftovers in the fridge for up to a week. (But, let's face it, you won't have any leftovers.)
Or store cider in freezer for up to 3-4 months.
Notes
*This is an estimate. Add enough to cover the fruit, once it's in your crock pot.