functions.php

<?php
/* 
 * Adds the placeholder {thumbnail:linked} for the shortcode [tribe_event_inline]
 * To be used as a new variable that outputs the thumbnail with a link to the event
 *
 * Author: Barry Hughes
 */

function do_linked_thumb_placeholder( $event_id ) {
    return '<a href="' . get_permalink( $event_id ) . '">' . tribe_event_featured_image( $event_id, 'full', false ) . '</a>';
}

function register_inline_linked_thumb_tag( array $placeholders ) {
    $placeholders['{thumbnail:linked}'] = 'do_linked_thumb_placeholder';
    return $placeholders;
}

add_filter( 'tribe_events_pro_inline_placeholders', 'register_inline_linked_thumb_tag' );