Where does “кле́тка” come from?

кле́тка (Russian) comes from Old East Slavic клѣтъка, from Proto-Slavic klětъka, from Proto-Slavic klětь, from Proto-Balto-Slavic klḗˀtis.

Ancestry of “кле́тка”, step by step

Step	Language	Word	Meaning
1	Old East Slavic	клѣтъка	—
2	Proto-Slavic	klětъka	—
3	Proto-Slavic	klětь
4	Proto-Balto-Slavic	klḗˀtis	—

кле́тка — Etymology, Origin & Word History | Etymology Explorer