Hi Ciaran,
I have another issue, I have set up a complete new Joomla 3 website and installed Clarity.
After that I still have access to the administrator, but the site shows this error:

Fatal error: Call to protected method JApplicationSite::route() from context '' in /var/www/xxx/html/joomla/index.php on line 36

I send you a link via email.

I have deleted the template and all plugins in case I used the joomla 2x files...but still the same error...do you have an idea, what could cause that? Thanks so much.
Regards B