oops, sorry about that. “Untested” 🙂 Try this, also untested!
<div class="staff-email">Email:
<a href="mailto:<?php echo antispambot(the_sub_field('staff_email_address')); ?>">
<?php echo antispambot(the_sub_field('staff_email_address')); ?>
</a>
</div>
If that’s working, make sure that the_sub_field('staff_email_address') is actually outputting an email address.
