It seems that Apple has removed legacy extensions from Safari Extensions Gallery and Clipper is no longer available if the users update the latest Mojave version or reinstall Clipper. A workaround is to install Clipper in other supported browsers such as Firefox or Chrome.
Webclipper and Safari 13 ?
in Web Clipper Issues
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It seems that Apple has removed legacy extensions from Safari Extensions Gallery and Clipper is no longer available if the users update the latest Mojave version or reinstall Clipper. A workaround is to install Clipper in other supported browsers such as Firefox or Chrome.