Any play up and down can't be fixed. I'm assuming your clutch lever is stock, in which case all the lever rotates on is a little brass bushing. They wear out like mad and then the lever moves up and down like you described. You have some options here: you could find a new bushing (or a ball bearing) to replace the old one (that'd be hard, Yamaha doesn't sell them), get an aftermarket lever, or an aftermarket lever, perch, the whole shibang. I'd recommend getting the whole shibang, the MSR ones are nice and they're SO easy to adjust.