Cryptic crossword clue
How rook flapping by motorway gets a parasite 8

The most common and most likely answer to this crossword clue is the 8 letter word HOOKWORM

I've seen this crossword clue in Independent
H
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Buddy explains!

The straight part
We know that "parasite" is the straight/definition part of the clue. The straight part is often a synonym or definition, in this case parasite = hookworm.
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 HOOKWORM mean?

HOOKWORM noun
  1. Any of various parasitic bloodsucking roundworms which cause disease, especially the species Ancylostoma duodenale and Necator americanus, having hooked mouthparts and entering their hosts by boring through the skin.

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