
1) Slavic god 2) Underworld god
Found on
https://www.crosswordclues.com/clue/chernobog

Chernobog ({proto|slavic|čĭrnŭ|black} and *bogŭ `god`), also spelled as Czernobog, Crnobog and Tchernobog is a Slavic deity, whose name means black god, about whom much has been speculated but little can be said definitively. The only historical sources, which are Christian ones, interpret him as a dark, accursed god, but it is questionable .....
Found on
http://en.wikipedia.org/wiki/Chernobog

In Slav mythology, Chernobog was the Black god of death, the adversary of the White god Byelobog.
Found on
http://www.probertencyclopaedia.com/browse/DCC.HTM
No exact match found.