I have a really uneven property, but I'm not a big fan of clean fill. Can I use cedar hog fuel instead of the fill? My plan is put around 12"- 24" of cedar hog fuel and put on the top about 6"-12" of topsoil, and just plant grass on it. Is this a good idea?
If you can, use only topsoil. If you have to use wood chips, cedar hog fuel is about the worst. It takes many years to break down fully. I don't think this is a good idea. You could use fill subsoil to bring up the soil line to 1' of where it needs to be, and use quality topsoil for the rest. 12-24" of any wood chips will require huge amounts of nitrogen to properly break down, and when they do, they will also shrink a good deal, often unevenly. This will not be good for lawn.
It's a similar idea to hugelkultur, and would work in some situations, but not as a substitute for soil in a lawn.
I'd do something else, personally.
"Topsoil" is expensive, at least in my neck of the woods, and so I can see the attraction to laying down something else first to help with the required volume to bring about the desired grade.
Anything with topsoil or compost in it is going to be expensive. I think locally topsoil runs maybe $20/yard and various combinations of topsoil and compost go up from there. It can get quite expensive quickly.
I can understand your thought about hog fuel - it's much cheaper than topsoil but while it would work in a hugelkultur scenario, I don't think it's likely to work well when you're trying to end up with something that is level or at least not uneven.
Here on my farm, hog fuel would work well as a bedding, particularly for my chickens, and in a season or so would break down considerably to the point where I could use it as an amendment to the soil. But it wouldn't produce that much volume.
Decomposition ends up reducing the volume of the inputs dramatically and while it would take time for those wood chips to break down under your topsoil, they will break down. Your ground wouldn't end up being even when it had decomposed. You could add more topsoil but that's not ideal.
If you could obtain hog fuel cheaply and if you had access to a load of chicken manure you could, assuming you had the desire, space and the equipment, mix that manure into the hog fuel, keep it moist and turn it periodically and you would see that Cedar break down - if you can keep the compost pile hot. Chicken manure is maybe 10:1 C:N while the hog fuel is... perhaps 100:1. A hot manure would break it down quite well. But most folks don't have a tractor with a front end loader or a Bobcat to do all the heavy lifting that such a pile would require and doing that by hand would be ridiculously labor intensive.
At least around here, fill dirt (mostly clay and rocks) is the cheapest thing in town. It's got the advantage that it won't setting nearly as much as something like hog fuel that will eventually decompose. If you had a foot of topsoil atop this fill dirt, you'd be doing better than most yards which have a scant amount of topsoil atop clay. I can appreciate not wanting to bring in fill dirt but it is usually one of the cheapest materials to use.
A friend had an uneven, sloped yard and he ended up terracing it, using landscaping timbers. He brought in topsoil but not that much of it. It turned out quite well and was a considerably less expensive route to go. Perhaps that would be an option for you. I offer it up as an alternative to what could be, depending upon the size of your yard, an expensive affair. Honestly, I liked the finished terrace look quite a bit and it would significantly reduce the volume of material you'd need.