The most common and most likely answer to this crossword clue is the 6 letter word SCRAMS
I've seen this crossword clue in The Daily Telegraph
S
C
R
A
M
S
Buddy explains!

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 SCRAMS mean?
SCRAMS verb- To use the shutdown or safety device of a nuclear reactor.
- (by extension) To use any emergency shutdown.
- Leave in a hurry, go away.
- Scratch with claws or fingernails.