My problem is now fixed. I did find a way to contact Evernote Support and for the record here was their suggestion which did work.
"It looks like this issue could be stemming from a problem with extension data in the Safari cache. To troubleshoot this issue, please try the following steps to deep clean the cache:
Uninstall the Evernote Web Clipper in Safari by navigating to Safari > Preferences > Extensions > Evernote Web Clipper and choose Uninstall
From the menubar, choose Safari > Clear History and choose All History then Clear History
On your keyboard, press ⌘ command + ⌥ option + esc simultaneously, then select Safari and choose Force Quit
Restart your Mac
Open Safari and install the Evernote Web Clipper from www.evernote.com/webclipper . If prompted to choose between installing the extension from the Safari Extensions Gallery or directly from the developper choose Install from Developer. This will ensure you install the latest version of the extension (version 6.9.4)."
Hope this is useful if others encounter this problem.