Overriding custom page variable
Try this:

/**
 * Variable preprocessor for the page template.
 */
function THEMENAME_preprocess_page(&amp;$variables) {
  if (arg(0) == 'classified') {
    // Do things here.
    $variables['my_new_variable'] = 'Something';
  }
}


Note that the template page-classified.tpl.php will also match all sub paths of that page too, like:
yoursite.com/classified/something
yoursite.com/classified/something/something