category specific most used tags query

I ended up doing this using wp_tag_cloud.

global $post;
//Tag Cloud
$cats = wp_get_post_categories( $post->ID );
$args = array(
    'category__in'          => $cats, 
    'showposts'             => -1
);
$custom_query = new WP_Query($args );
if ($custom_query->have_posts()) :
while ($custom_query->have_posts()) : $custom_query->the_post();
    $posttags = get_the_tags();
    if ($posttags) {
        foreach($posttags as $tag) {
            $all_tags[] = $tag->term_id;
        }
    }
endwhile;
endif;

$tags_arr = array_unique($all_tags);
$tags_str = implode(",", $tags_arr);

$args = array(
'smallest'  => 18,
'largest'   => 18,
'unit'      => 'px',
'number'    => 10,
'orderby'   => 'count',
'order'     => 'DESC',
'format'    => 'flat',
'include'   => $tags_str
);
echo '<div class="tag-top"><h4>Popular Tags within: ';
single_cat_title();
echo '</h4>';
wp_tag_cloud($args);
echo '</div>';