local/Cybergroup/RemoveCC/Model/Cron.php

<?php
Mage::log(__FILE__);

class Cybergroup_RemoveCC_Model_Cron
{

  public function removeOldCcNumbers()
  {
    mail('test@example.com', 'test cron', 'Testing the cron setup.');
    //$order->getPayment()->setData('cc_number_enc', null);
  }
}

local/Cybergroup/RemoveCC/etc/config.xml


<config>
  <global>
    <modules>
      <Cybergroup_RemoveCC>
        <version>0.1.0</version>
      </Cybergroup_RemoveCC>
    </modules>
    <models>
      <cybergroup_removecc>
        <class>Cybergroup_RemoveCC_Model</class>
      </cybergroup_removecc>
    </models>
    <crontab>
      <jobs>
        <cc_remove>
          <schedule>
            <cron_expr>* * * *</cron_expr>
          </schedule>
          <run>
            <model>cybergroup_removecc/cron::removeOldCcNumbers</model>
          </run>
        </cc_remove>
      </jobs>
    </crontab>
  </global>
</config>