The most common and most likely answer to this crossword clue is the 4 letter word LABS
I've seen this crossword clue in Independent
L
A
B
S
More clues leading to the result LABS
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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 LABS mean?
LABS noun- A laboratory.
- (chiefly in the plural) Laboratory experiment, test, investigation or result.
- A Labrador retriever.
- A telltale; a blabber.