Widen your pattern, relax your shoulders, throw close to your chest/face, but off to the side. Practice against a wall if you have to, off the unicycle. If you do club passing, you should be familiar with making your pattern wide so you can get under it. When idling, it’s so your hands can stay by your side. Work on minimizing the movement of your elbows when juggling clubs. Make it mostly forearm movement. Make sure you’re sitting up straight and your back is in the same position it would be without juggling. (don’t lean towards the clubs)
Make sure you’re sitting on the seat and idling lightly. Try idling at different speeds, keep your juggling at a comfy pace, don’t try and change the height/timing to suit the speed of the idle. Practice that kind of club control off the wheel. If you need to tweak it a bit, that’s fine, but no super crazy high lofty throws that allow you to throw, then recapture your balance between throws. That’s cheating and wont get you much progress.
Focus on the thing that you aren’t as good at. It’s a general rule of thumb when practicing multiple tricks at the same time. It sounds like you may be better at unicycling than juggling, in which case make darn sure you keep all the focus you need on the juggling, and if you fall off the wheel, that’s fine. I had to do that for learning to balance a club on my head while juggling. Had to focus on balancing, and let the clubs fall if things got out of control to make SURE I would prioritize the balance no matter what.
Lastly, change up the way you practice often. Try riding forward, getting the juggle going, then bringing the wheel to an idle until you feel things start to fall apart, then ride forward again (which is much easier to juggle while doing) and get it back under control. Rinse and repeat. Then try idling and doing 3 throws at a time, stopping, going back to an idle again. Come up with your own ways to get in and out of juggling + unicycling, and change it often. The more ways you can come up with, the faster you’ll learn. You just have to get your brain to think about it in a lot of different ways until something sticks.
edit: I would recommend getting some cheap, one piece clubs, like dube airflights if you’re worried about damaging them. If you are working with wooden-core clubs, like renegades, yes, you could potentially break one if you came down on it, but it’s more likely that you’ll break one from stepping on one rather than riding over one. A club will just shoot out from under the wheel if you happen to hit it while idling/riding. You’d have to hit it just right to break it by riding over it. Keep that in mind, if you drop, just keep idling and you’re very unlikely to damage it if you come off the wheel controlled. If you’re working with plastic-core clubs like PX3s, they’ll just bend, don’t worry about it. The one piece airflights are good for parades, you can tape them up for the occasion if you get white ones, they’ll go with everything, and they’re incredibly durable on concrete/asphalt, so they’re right at home in a parade, but they will force you to juggle properly so you don’t hurt your hands. They’re not as soft as a typical club with a wrapped handle, so just keep that in mind, or wear gloves or something. Lastly, if they are someone else’s clubs, try and use ones that are relatively new, so if you break one, you’re not breaking in one of their nice, worn in clubs. Buying a new club for a friend is no big deal, but if they have an old set, a new one won’t fit in to the set properly… nobody juggles my worn clubs but me. : P