blur gets cropped

I wanted to use blur on a stroke that is white. When using blur value of 1 or greater, part of the blurred portion is cropped by the edge of the bounding box.

What I hoped to achieve is to have a white blurred arc, but the only way I have found to do this is to use the stroke color of white on a stroke of sufficient width (I need a circular arc here). When circular paths are built using the oval tool, they are always filled.

That means a lot of extra work to get the effect I am looking for. In this case, I can't make it look right possibly due to a limitation of the program.

Path gradients would be the perfect solution, but it looks like we aren't there yet.

Is there a way to get rid of clipping by the bounding box?