<?php
    $str = '<ul class="top"><li><a href="[T]XX[/T]">Testing</a></li></ul>';
    $str = '<?xml encoding="utf-8" ?>'.$str;
    $dom = new DomDocument();
    @$dom->loadHTML($str);

    $xpath_menu_bottom = new DomXpath($dom);

    $x = $xpath_menu_bottom->query('(//ul[@class="top"])[1]')->item(0);

    var_dump($dom->saveHTML($x));
?>