The most common and most likely answer to this crossword clue is the 5 letter word ORCAS
O
R
C
A
S
More clues leading to the result ORCAS
- Run around, trapped by unusually big predators
- A danger to other remaining creatures at sea, initially?
- Particularly large guards right about killers, in the main
- Main residents of Windsor Castle
- Oceanic residents cruising around sea initially
- No dodgy cars in Wales reportedly
- Poor casting includes predators in the main
- Large guards over Richa’s odd sea creatures
- Giant killers involved in major case
- Comes a cropper holding up killers
Buddy explains!

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