Wordpress shortcode based on Advanced Custom Fields' standard shortcode that adds the ability to specify which part of a 'link' field to return. Options for 'element' are url, title or target.

functions.php

/* Enhanced ACF link shortcode. Return format must be array for this to work
   Element can be url, title or target
   Example: [acf_link field="my_link_field" post_id="1000" element="url"] (returns the URL of the link)
   Example: [acf_link field="my_link_field" post_id="1000" element="title"] (returns the title of the link)
*/

function acf_link_shortcode($atts)
{
	extract(shortcode_atts(array(
		'field'			=> '',
		'post_id'		=> false,
		'element'	 	=> 'url'
	), $atts));

	$link =	get_field($field, $post_id);
	$value = $link[$element];

	return $value;
}

add_shortcode('acf_link', 'acf_link_shortcode');