tldr

<?php

function tldr_shortcode() {
    global $post;
    if (function_exists('get_field') && get_field('tldr')) {
        $content = get_field('tldr');
    }
    elseif (has_excerpt()) {
        $content = get_the_excerpt();
    }
    else {
        return '';
    }

    return '<div class="tldr-excerpt"><p>' . wp_kses_post($content) . '</p></div>';
}
add_shortcode('tldr', 'tldr_shortcode');
?>
<?php