is to pull up a zonemapper, and, using zonefinder view, just mouse over the top or bottom zones, and you'll see in the zonefinder the yellow indication. adjusting the zoom will give you an even better sense of it.

now, that top zone has a lot of data in it, so it's a bit broad, but that's still should give you some indication of potential problems. the thing about clipping, however, is that in raw at least it can be a little tricky to know when something is really clipped, because the recovery potential may be large. that's going to vary from profile to profile and camera to camera.

IMO, you're better off becoming intimate with your camera's files and how they present in a histogram. i can pretty much tell whether i've got unsalvageable clipping just looking at that. also, checking problem spots with the sampler will give you a real good idea of what is actually irretrievably clipped. for me, anything above 9.8 is usually gone. and on the dark end of the scale, that's also a matter of how you like your shadows. personally, i think there's a lot more leeway there, especially in B+W. i think psychologically viewers are better able to accept no detail in really deep shadows.