Anyway to clear brush from settlements?

There is no way to remove it without using the console. With the console, I believe you should be able to open the console, click on the scrub to select it, and type "disable" in the console. I've never used this on shrubs, but it's worked on everything else I've tried it on.

Another option, while not removing it, would be to use the platform floors or the foundations to raise all your buildings above the level of the scrub.

There are a few mods that help with that. I use Spring Cleaning.

Spring Cleaning allows for the removal of trash and clutter objects originally unable to be scrapped within settlements.

A video of Spring Cleaning in action: