Across:
0. One letter replaced, I am your relative. (4 letters)
1. One letter replaced, I am a country. (3 letters)
4. One letter replaced, I am vehicles. (5 letters)
6. Two letters replaced, you call me. (4 letters)
7. One letter replaced, I start. (5 letters)
Down:
2. One letter replaced, I am a singer. (5 letters)
3. A Korean beer. (5 letters)
5. One letter replaced, I am a mammal. (5 letters)
8. One letter replaced, I am surjective. (4 letters)
9. One letter replaced, I am a bird. (4 letters)
IMPORTANT!:
The "words" are incomplete. Consider the oddity, and you'll see their complete version.
Subtle Hint:
The "words" are incomplete, as they are just prefixes of the complete versions.
Moderate Hint:
To be complete, they require suffixes, which are complete words themselves.
Decisive Hint:
The suffixes are already shown.
Very Decisive Hint:
Revelation 1:8, Revelation 21:6, Revelation 22:13.
Very² Decisive Hint:
Bravo!
Very³ Decisive Hint:
https://www.hitejinro.com/ (Not an advertisement, but one of the words is shown here.)