In the CMS editor, it is technically not feasible to enclose <div> elements within <a> elements. Instead, you have the option to include specific attributes to the <div> elements:
data-widget-link-hrefdata-widget-link-target (optional)data-widget-link-class (optional)
For example, setting in the editor these attributes in such way (please use the sidebar for this, there is no need for Source dialog here):
<div data-widget-link-href='http://example.com' data-widget-link-class='cls1' data-widget-link-target='_blank'>...</div>
will convert this <div> into a <a href><div> structure:
<a href='http://example.com' class='cls1' target='_blank'>
<div>...</div>
</a>
