Where does “клати” come from?

клати (Old Church Slavonic) comes from Proto-Slavic kòlti — to stab, to sting; to sting.

Ancestry of “клати”, step by step

Step	Language	Word	Meaning
1	Proto-Slavic	kòlti	to stab, to sting; to sting

клати — Etymology, Origin & Word History | Etymology Explorer