The most common and most likely answer to this crossword clue is the 6 letter word SCOLEX
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Buddy explains!
The straight part
We know that "Hooked head" is the straight/definition part of the clue. The straight part is often a synonym or definition, in this case hooked head = scolex.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 SCOLEX mean?
SCOLEX noun- The structure at the front end of a tapeworm which, in the adult, has suckers and hooks by which it attaches itself to a host.