Show articles from a certain category and tag

How can i display all the articles belonging to a tag but only from a certain category?

In fact i have a page that lists all artists, each artist is a tag. Each artist has songs and each song belongs to a specific category. I want to be able to show users all articles (songs) from a tag (artist) belonging to a specific category.

How can i do that? Thanks in advance.

Here’s my tag.php file:

[code moderated – please use the pastebin]

Also i had to hook pre_get_posts to order by title and ascending:

function my_pre_get_posts($query)
{
	if(is_tag())
	{
		$query->set("orderby", "title");
		$query->set("order", "asc");
	}

	return $query;
}