The most common and most likely answer to this crossword clue is the 4 letter word SLEW
I've seen this crossword clue in Independent
S
L
E
W
More clues leading to the result SLEW
Buddy explains!

The straight part
We know that "killed/a great number" is the straight/definition part of the clue. The straight part is often a synonym or definition, in this case killed/a great number = slew.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 SLEW mean?
SLEW noun- The act, or process of slewing.
- A device used for slewing.
- A change of position.
- To rotate or turn something about its axis.
- To veer a vehicle.
- To insert extra ticks or skip some ticks of a clock to slowly correct its time.
- To pivot.
- To skid.
- To move something (usually a railway line) sideways
- To make a public mockery of someone through insult or wit.
- A wet place; a river inlet.
- To kill, murder.
- To eradicate or stamp out.
- (by extension) To defeat, overcome (in a competition or contest).
- To delight or overwhelm, especially with laughter.
- To amaze, stun or otherwise incapacitate by awesomeness; to be awesome at something; to kill (slang sense).
- To have sex with
- A large amount.