I hope that I can explain clearly. Make sure it is out of gear.
Bend the tab on the washer so that you can get a socket with a short extension on it.
Using the longest breaker bar you have rotate it as smartly and as quichly as you can in the clockwise direction.
This will cause the whole assembly to turn.
Have something like a block of hardwood placed in the way of the breaker bar, where the end will hit, so that it comes to an abrupt halt.
The inertia of the spinning clutch, shoud keep it spinning just enough to loosen the nut.
You may needs to do this a few times, but has always worked for me in an emergency.
This method of loosening nuts is very usefull when changing grinding wheels and circular saws, where you have nothing to grab on to to hold them.