You do this with a memberOf filter in your LDAP Import Settings Base filter field, like this
(memberOf=CN=QCUSERS) in addition to your Base directory entry, probably something like (OU=Role,OU=Groups,OU=Production,DC=company,DC=com).
When you do the import, only members of the QCUSERS group will be imported. Unfortunately, this only imports a set of users into QC. If a user is removed from the active directory group, the import will not remove them from the QC user list. However, you can use a OTA script to do this.