Example of how to remove the site name from the gateway order descriptions

tw_ee_EE_Gateway___order_description.php

<?php
//* Please do NOT include the opening php tag, except of course if you're starting with a blank file

add_filter('FHEE__EE_Gateway___order_description', 'tw_ee_EE_Gateway___order_description', 10, 3);
function tw_ee_EE_Gateway___order_description( $desc, $gateway, $payment ) {
    return sprintf(
        esc_html__('Event Registrations for %1$s', "event_espresso"),
        $payment->get_first_event_name()
    );
}