How can we add the embedded file inside the Excerpt field?

The excerpt field is designed to be a post summary, so it is generally strange to embed something there besides text. In general it is up to the theme creator to enable shortcode support within this area. However if you have the ability to insert php code, or use a plugin designed to enable this, or have direct access to edit the theme (or better to create a child theme) you may be able to add this line of code to its functions.php to enable:

add_filter('the_excerpt', 'do_shortcode');

or else use try using the do_shortcode command directly.