How to use wp query posts with current post meta value in text widget

Your question is a bit hard to read, but if I understand you on a single post page this should work:

$obj = get_queried_object();

if ('WP_Post' === get_class($obj)) {
  $cellar = get_post_meta($obj->ID,'cellar_slug',true);
  if (!empty($cellar)) {
    $cellars = new WP_Query(
      array(
        'post_type' => 'post', 
        'numberposts' => -1, 
        'posts_per_page' => '1',
        'meta_query' => array(
        array(
          'key' => 'cellar_slug',
          'value' => $cellar,
        )
      ),
      'orderby' => 'menu_order', 
      'order' => 'ASC'
      )
    );
  }
}

You are:

1. Using get_queried_object() to grab the main post data
2. Using get_post_meta() to retrieve the cellar associated with the
   post
3. And running the query only if you have a cellar