clipgrab is an AUR package — and it doesn’t have anything to do with Xfce, GNOME, Plasma or whatever. 
sudo pacman -Syu clipgrab
… or…
pamac update
You should also install rebuild-detector from the Manjaro repository if you don’t have it installed already. I’ll tell you which packages from the AUR need a rebuild whenever the system is updated.
sudo pacman -S rebuild-detector
… or…
pamac install rebuild-detector