WordPress: Sortable Columns (Backend) http://www.elliotcondon.com/advanced-custom-fields-admin-custom-columns/

wp_sortable_columns.php

function iz_post_column_register_sortable( $columns )
{
	$columns['author'] = 'author';
	$columns['categories'] = 'categories';
	$columns['tags'] = 'tags';
	return $columns;
}
add_filter("manage_edit-post_sortable_columns", "iz_post_column_register_sortable" );
// add_filter("manage_edit-CPT_SLUG_sortable_columns", "iz_post_column_register_sortable" );