Motorcycles

First what year make and model is this bike?

Okay it sort of sounds like you're new to working on your bike. That's totally okay we all have to start somewhere, but it is important to know what you're doing before you do it. If you don't you can cause mechanical failure and or crash.

So that nut near your clutch lever is for adjusting clutch free play. As you put miles on a bike the cable for the clutch stretches. So periodically you have to adjust the cable so it is at the right tightness again. If you do this incorrectly you can cause engagement and or disengagement problems. Also you have the potential to burn your clutch up.

The first thing you need to do is look up a good tutorial on setting clutch replay. If you go to YouTube and search "RevZilla shop manual clutch free play" there's a quick little video by Arie Henning that's a pretty good explanation. You will need your specific bikes clutch free play though.

Second this seems much more like you either need to lube your clutch cable or there's something wrong in your clutch basket. Personally I would lube up your clutch cable. And maybe replace it if it pushes out a lot of rust.

If you are as new to motorcycle maintenance as I think you are. I would not make opening up your clutch basket your first activity. It's not too hard but it might be helpful to have a friend who knows a bit more about it to help you and so you can. Learn.