Cambialo asi:
Código PHP:
<?php
$hostname_conect = "localhost";
$database_conect = "clientes";
$username_conect = "paco";
$password_conect = "bexbex";
$conect = mysql_connect("$hostname_conect", "$username_conect", "$password_conect") or die(mysql_error("Error al conectar a la base de datos"));
mysql_select_db ("$database_conect", $conect);
?>
Salu2