When adjusting the flower nut on the clutch, make sure that you have the clutch lever pulled in and locked in place.
Tighten the flower nut until you can't turn the back wheel at all, from there, turn the nut counter clockwise a "notch" at a time until you get the wheel to turn freely by hand and stop right there and put the lock screw back in place at that notch where the wheel just starts to turn freely.
When you release the lever it should of course be totally locked up and at this point you should have all the slippage out of it.