Drupal 7 Field api checkbox not saving
===

I'm trying to get a Drupal 7 Field working programmatically and it's not going well.
I simply want to create a module that creates a Field with a checkbox. The module is working, the field is working but the checkbox will not save.

Here is my hook_field_widget_form:

    <?php
    function add_to_basket_field_widget_form(&$form,&$form_state,$field,$instance,$langcode,$items,$delta,$element)
    {
    	$element += array(
    		'#type' => 'checkbox',
    		'#title' => t('Add to basket?'),
    		'#default_value' => isset($item['add_to_basket_cfield']) ? $item['add_to_basket_cfield'] : '',
    	);
    	return $element;
    }
    ?>


When I run it as part of my module it works but wont save a tick or no tick.
I've tried everything I can think of to get this working but after 3 days with nothing to show it's time to ask the experts

Thanks