Is it motor oil or hydraulic fluid? Either way good chance it's an easy fix. You have to remove the side cover and in order to do that you'll have to remove the left foot board and both shifter pedels. Careful removing the foot board spring, safety glasses would be a good idea here. Four bolts and the side cover is off. You'll probably find the fluid leaking from under neath the clutch rod actuator. That's the piece at the back that your clutch hose is screwed into. That thick black gasket looking thing under the actuator is not a gasket, it's a plastic spacer with a weep hole drilled in the bottom. The weep hole is there so if your clutch push rod seal or actuator piston gasket goes bad oil or hydraulic fluid will leak out to notify you that it needs replacing.
Remove the three small bolts holding the actuator on and let it dangle. On the motor where the actuator was mounted you'll see the push rod sticking out and a small round black seal around it inserted into a recess in the motor. If the seal has popped out of place and is hanging on the push rod you just found your problem. You can buy a new seal at your Kawasaki parts counter for under $10. Use a socket as a setpunch to GENTLY drive the new seal in flush with the motor being careful not to drive it all the way thru the hole. Installing the seal with finger pressure only is not enough, it WILL pop out again.
Some notes here:
1) There is an inside and outside to the seal . Pay attention to how the old one was inserted when removing it.
2) The push rod has a flat end and a rounded end. The flat end inserts into the motor and pushes angainst the clutch. Put a dab of grease on it when installing. Put a little oil on the rod part that slides in the seal so the seal is not dry.
3) If the push rod surface is rough polish the part that moves inside the seal shiny smooth with steel wool. If you dont it acts like a round file and wears the new seal out.
4) Don't pull in the clutch lever with the actuator removed. If you do all the guts inside the actuator will spit out on your shop floor.
Okay, now for the other possibility. Theres another seal inside the actuator you just removed . If it leaks hydraulic fluid will drip out the same weep hole mentioned earlier. If your leak is a hydraulic leak replace that seal...also available at your Kawa dealer for under $10.
Reassemble and ride!
This all sounds a lot more complicated than it really is. It's a simple repair you can do with common tools, probably in less than 2 hours. I've done it three times now and have the whole procedure down to under an hour.
Hope this helps !