WordPress at a glance
action is not described

clean_user_cache action-hook . WP 4.4.0

Fires immediately after the given user's cache is cleaned.

Usage

add_action( 'clean_user_cache', 'action_function_name_7487', 10, 2 );
function action_function_name_7487( $user_id, $user ){
	// action...
}
$user_id(int)
User ID.
$user(WP_User)
User object.

Where the hook is called

clean_user_cache()
clean_user_cache
wp-includes/user.php 1313
do_action( 'clean_user_cache', $user->ID, $user );

Where the hook is used (in WP core)

Does not used.