$re = '/\((?=([^\(\)\[\]]*(\b)(ARR|ARRANGEMENT|ARRANGEMENTS|ARRANGED|CHOPPED|DUB|EDIT|FT|FEAT|FEATURING|INSTRUMENTAL|MASH UP|MASHUP|MASH-UP|MIX|REMIX|REPRISE|SCREWED|TITLE|VERSION)(\b)[^\(\)\[\]]*)).*?\)/';
$str = '';
$subst = "\1";
$result = preg_replace($re, $subst, $str);
echo "The result of the substitution is ".$result;
Please keep in mind that these code samples are automatically generated and are not guaranteed to work. If you find any syntax errors, feel free to submit a bug report. For a full regex reference for PHP, please visit: http://php.net/manual/en/ref.pcre.php