How to make seen categories even if forums are not seen?

How to make seen categories even if forums are not seen?

In my forum is subforum only for women. Guests can not see it. This women subforum is alone under one category which name ~~~ is "Women only forums".

But guests or even members who are not women can not see this category.

But I want that they know that such forum exist, so female guests would be motivated to register.

So I want that dispite that guests (and other ordinary memebers) can not see forum, they could see category in which is this forum.