The most common and most likely answer to this crossword clue is the 4 letter word CAWS
C
A
W
S
Buddy explains!
The straight part
We know that "ravens’ calls" is the straight/definition part of the clue. The straight part is often a synonym or definition, in this case ravens’ calls = caws.The cryptic/wordplay part
In cryptic crossword there's often an wordplay/cryptic part as well.This part involves a more complex hint, such as an anagram, homophone, hidden word, etc.
Sadly, We don't have an explanation for this specific crossword clue yet.
What does CAWS mean?
CAWS noun- The harsh cry of a crow.
- To make the harsh cry of a crow, rook, or raven.