Ok – I understand now. I added this to my functions.php. This, however, it now adds an additional description the .ics (there are now 2 descriptions). How can I have this description replace the original, instead of adding to it?
add_filter( ‘tribe_ical_feed_item’, ‘filter_ical_item’, 10, 2 );
function filter_ical_item( $item, $eventPost ) {
$item[] = ‘DESCRIPTION:’ . get_the_excerpt();
return $item;
}