Plugin request?

I’m unsure if theres a forum actually for this but i didn’t see it so sorry if i’m posting in the wrong place.

I was just wondering if theres a plugin which could do the following:
I want to make a category “private” so that only the administrator can post in that category but everyone else can still view the posts in the category.

This would work well for people who want a “site announcement” type category 🙂