The most common and most likely answer to this crossword clue is the 7 letter word STIFLES
I've seen this crossword clue in The Guardian
S
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Buddy explains!
The straight part
We know that "Clamps down on/Clamps down on" is the straight/definition part of the clue. The straight part is often a synonym or definition, in this case clamps down on/clamps down on = stifles.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 STIFLES mean?
STIFLES noun- A hind knee of various mammals, especially horses.
- A bone disease of this region.
- To interrupt or cut off.
- To repress, keep in or hold back.
- To smother or suffocate.
- To feel smothered etc.
- To die of suffocation.
- To treat a silkworm cocoon with steam as part of the process of silk production.