Safari fonts: Verdana not rendering

Verdana is not rendering correctly in Safari 12, now that I have upgraded to Mojave.

I found this reply in another conversation. It is the same situation for me: "After looking at Verdana in Font Book I noticed that two versions were installed. One inside the default /Library/Fonts folder which had been disabled and one inside /Library/Fonts/Microsoft. Font Book "resolved" these duplicates (I assume when Mojave was installed) by disabling the default /Library/Fonts file."

The answer suggests right-clicking on the 'Off' font (the one in /Library/Fonts file) and selecting 'Enable'. But when I try that, 'Enable' is not one of the options, only 'Disable'??

What else is possible here please?