Strip out HTML and Special Characters

Strip out tags, leave only alphanumeric characters and space:

$clear = preg_replace('/[^a-zA-Z0-9\s]/', '', strip_tags($des));

Edit: all credit to DaveRandom for the perfect solution...

$clear = preg_replace('/[^a-zA-Z0-9\s]/', '', strip_tags(html_entity_decode($des)));

Probably better here for a regex replace

// Strip HTML Tags
$clear = strip_tags($des);
// Clean up things like &
$clear = html_entity_decode($clear);
// Strip out any url-encoded stuff
$clear = urldecode($clear);
// Replace non-AlNum characters with space
$clear = preg_replace('/[^A-Za-z0-9]/', ' ', $clear);
// Replace Multiple spaces with single space
$clear = preg_replace('/ +/', ' ', $clear);
// Trim the string of leading/trailing space
$clear = trim($clear);

Or, in one go

$clear = trim(preg_replace('/ +/', ' ', preg_replace('/[^A-Za-z0-9 ]/', ' ', urldecode(html_entity_decode(strip_tags($des))))));