hook_menu() should use include file and HTML tags should not be used in translatable strings

Your code is given below.

/**
 * Implements hook_menu().
 * Add the clear_cache menu link text, and link it to the clear_cache_truncate() function
 */
function clear_cache_menu() {
  $items = array();
  $items['admin/clearcache'] = array(
    'title' => 'Clear Cache',
    'page callback' => 'clear_cache_truncate',
    'access arguments' => array('use clear cache'),
    'type' => MENU_NORMAL_ITEM,
    'weight' => 16,
  );
  return $items;
}
module_load_include('inc', 'clear_cache', 'clear_cache.clear');

Module should not use module_load_include directly in module file, better to use file or file path.

"file": A file that will be included before the page callback is called; this allows page callback functions to be in separate files. The file should be relative to the implementing module's directory unless otherwise specified by the "file path" option. Does not apply to other callbacks (only page callback).
"file path": The path to the directory containing the file specified in "file". This defaults to the path to the module implementing the hook.

reference: https://api.drupal.org/api/drupal/modules%21system%21system.api.php/func...

drupal_set_message(t('Success &#x270c; <br/>All Drupal Caches cleared.'), 'status');

t() translate the string, in this case
tag will also translated.