Steps to Create a copy of a Drupal 7 website using cpanel?
Here are the steps I would take in cloning the site. First, Create the subdomain. Then copy all the files from the live site to the subdomain. Then I would back up the database. Create a new database and import the backup into that. Assign the user from the first database to the second one. Then change the settings.php file to read from the second database. Also, if you have a base url set in settings.php you would need to change that as well. Hope that helps.