gistfile1.php

  	$menu = wp_nav_plus(array('menu' => $instance['menu_term_id'], 'echo' => false, 'container' => false, 'items_wrap' => '%3$s', 'start_depth' => $instance['start_depth'], 'depth' => $instance['depth']));
		if(!empty($menu)) {
      echo 'your container html';
			echo $menu;
      echo 'end your container html here';
		}