description_under_label.php

<?php
/**
 * Move the description under the label for product add-ons
 */
function prefix_field_description_list_layout( $item, $id, $group_layout, $file ) {
	pewc_field_description( $item, $id, $group_layout );
}
add_action( 'pewc_before_include_frontend_template', 'prefix_field_description_list_layout', 10, 4 );

// Remove the description field from after the field
remove_action( 'pewc_after_field_template', 'pewc_field_description_list_layout' );