The most common and most likely answer to this crossword clue is the 4 letter word ROTS
I've seen this crossword clue in The Daily Telegraph
R
O
T
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 ROTS mean?
ROTS noun- The process of becoming rotten; putrefaction.
- Decaying matter.
- Any of several diseases in which breakdown of tissue occurs.
- Verbal nonsense.
- To suffer decomposition due to biological action, especially by fungi or bacteria.
- To decline in function or utility.
- To (cause to) deteriorate in any way, as in morals; to corrupt.
- To make putrid; to cause to be wholly or partially decomposed by natural processes.
- To spend a long period of time (in an unpleasant place).
- To expose, as flax, to a process of maceration, etc., for the purpose of separating the fiber; to ret.
- To talk nonsense.