functions.php

add_shortcode('post_image_website_link', 'post_image_website_link');
function post_image_website_link($atts) {
 	$postID = get_the_ID();
    $website_link = geodir_get_post_meta( $postID, 'website', true );
    $thumbnail = get_the_post_thumbnail( $postID, 'full' );

    return '<div class="featured-image">'
    . '<a href="' . $website_link . '">'
    . $thumbnail
    . '</a>'
    . '</div>';
}