The most common and most likely answer to this crossword clue is the 8 letter word ANEURYSM
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Buddy explains!
The straight part
We know that "swelling in the artery" is the straight/definition part of the clue. The straight part is often a synonym or definition, in this case swelling in the artery = aneurysm.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 ANEURYSM mean?
ANEURYSM noun- An abnormal blood-filled swelling of an artery or vein, resulting from a localized weakness in the wall of the vessel.