Your chain might be a little too long (but then again, if you are on a FS this might be required to account for chainstay growth during shock travel). Running a long cage on a single ring set-up is less than ideal as well. Short or medium cage is best IME. If its a Shimano clutch, then might also be worth checking how the clutch is set, as they are user serviceable (you can increase/decrease the clutch tension).
Silly question - but you have got the chainring on the inside of the spider (where the middle ring would sit), not the outside? If so, and its still dropping off the inside, you could always swap the BB spacer over to the non-driveside, which in effect moves the chainline inboard.
It sounds a set-up issue though, so worth playing around and making sure everything is set-up right. It kinda defeats the point of running clutch mechs and NW chainrings, to still run a bash and a chainguide (unless of course you are smashing fast, uber-tech trails)