How to clear or update only anonymous cache from module?
cache_clear_all() is what you need.

If you need to clear cache of only one node page:

cache_clear_all('http://yoursite.com/node/' . $node-&gt;nid, 'cache_page')


(first parameter - cache id, it case of cache_page it is page url).

If you want to clear all pages cache:

cache_clear_all('*', 'cache_page', TRUE);