The most common and most likely answer to this crossword clue is the 8 letter word THICKENS
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Buddy explains!
The straight part
We know that "Clots" is the straight/definition part of the clue. The straight part is often a synonym or definition, in this case clots = thickens.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 THICKENS mean?
THICKENS verb- To make thicker (in the sense of wider).
- To make thicker (in the sense of more viscous).
- To become thicker (in the sense of wider).
- To become thicker (in the sense of more viscous).
- To strengthen; to confirm.
- To make more frequent.