The most common and most likely answer to this crossword clue is the 4 letter word ORCA
O
R
C
A
More clues leading to the result ORCA
- Killer whale in major catastrophe
- Large predator in Windsor Castle
- What’s found in school in West Coast states
- Other ranks caught a killer whale
- Killer is nonracial, which is oddly overlooked
- Whale heads for ocean reef, cruising around
- Whale with teeth decapitated Spanish poet
- Legendary monster bore scar centrally
- Predator in the main features in “An Inspector Calls”
- Sea creature half-visible from Orkney
Buddy explains!

The straight part
We know that "killer whale" is the straight/definition part of the clue. The straight part is often a synonym or definition, in this case killer whale = orca.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 ORCA mean?
ORCA noun- A sea mammal (Orcinus orca) related to dolphins and porpoises, commonly called the killer whale.