Hi,
There is an easy grade 1 scramble near the top of the grindsbrook path. Just as the main path starts it's final steep rough section onto the plateau, there's a right turn onto a path that follows the right branch of the stream (right hand when looking up) and you can see a narrowing clough when you look along it. The path turns into a scramble - I think the difficulty of this would be more than you are looking for. It's easiest when bone dry, harder when the stream is flowing (the easiest steps are in the bed of the stream in places). If you follow the left path, it's steep and rough, but not a scramble, as others have said. I do tend to use my hands in places, though, and it feels steeper coming down.
A couple of asides: part way up the right hand branch (the scramble route), as the "gorge" narrows, there's a scramble up a small waterfall on the left wall - I've never tried this, but it's definitely harder -I didn't like the look of it when I had a quick look in the summer (I think it's winter grade II when frozen). The scramble in Crowden clough is a bit more serious, as has also been said -there's a 8 metre (?) steep section by a waterfall (again slightly easier when dry as can go up the stepped waterfall). A slip here would be serious. There is also a path which heads off to the left up on to the plateau before the scramble starts (to do the scramble you would need to follow the stream closely).
Jon.