The most common and most likely answer to this crossword clue is the 8 letter word EMBOLISM
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Buddy explains!
The straight part
We know that "causes obstruction of blood vessel" is the straight/definition part of the clue. The straight part is often a synonym or definition, in this case causes obstruction of blood vessel = embolism.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 EMBOLISM mean?
EMBOLISM noun- An obstruction or occlusion of an artery by an embolus, that is by a blood clot, air bubble or other matter that has been transported by the blood stream.
- The insertion or intercalation of days into the calendar in order to correct the error arising from the difference between the civil year and the solar year.
- An intercalated prayer for deliverance from evil coming after the Lord's Prayer.