How to : need approval for group creation in a category ??

Hello,

I wonder how to achieve that :

For one group category i would like : the user can propose the creation of a new group but needed approval of admin...

I can't find where to achieve that
in category settings i just can specified witch user profile is allowed to create groups in this category... but i can see a "pending approval" in the menu... so maybe this approval settingalready exist...

An you help me in that please
Loïc