Try a query more like:
PHP Code:
$getrepx = $db->query_read("SELECT userfield.field8, user.userid, user.username
FROM " . TABLE_PREFIX . "userfield
LEFT JOIN " . TABLE_PREFIX . "user
ON (user.userid = userfield.userid)
ORDER BY userfield.field8 DESC LIMIT 10");
Not knowing how you are putting this into the page though doesn't help us figure out why nothing is displaying. You really need to post the part where you add it to the template - both the php page and what is in the template.