Using Query posts to get child posts

Hi, i’m trying to get hold of certain posts – and its really doing my head in. I’m writing some SQL code at the moment but maybe someone knows a way to use the wordpress functionality.

The top level is a custom post type area called “Clothing”

Next, there are some parent categories which are brands like “next”, “levi”, “oakley” etc

After this there are children or each brand such as “tops”, “trousers”, “jumpers” etc

I need to call this information a few ways, most of which I have figured out. Here they are;

1) Call ALL Clothing posts on one page. I use query_posts and post_type = “clothing” – works ok.

2) Call a page with all items from a brand. Im using query_posts and clothing => “next” (or any other brand. Works ok.

3) The problem. I need a page that will call ONLY one type of clothing that a brand makes. For example “Next” => “Tops”. Maybe I have missed something obvious, I can’t find a way to do this. In the admin panel I have the parent “next” and the child “tops” both ticked in the categories area.

Please help me, i’m trying all sorts of stuff but one of you might know the answer. Maybe the system need structuring differently?

Dan