The most common and most likely answer to this crossword clue is the 7 letter word ANNELID
I've seen this crossword clue in The Daily Telegraph
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More clues leading to the result ANNELID
- Leech, perhaps, queen stuck on cap
- Bin Laden trained missing book worm
- Worm found by queen once on hat
- Worm if old and lined wriggles
- Type of creature destroyed by lindane
- Girl of 5, dreadfully idle worm
- Girl with hat is a leech, for example
- Girl under cover finds something crawling
- Banned slide — shedding skin like a worm
- Fish bait and line assembled
Buddy explains!

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 ANNELID mean?
ANNELID noun- Any of various wormlike animals, of the phylum Annelida, having a segmented body; they include the earthworm and the leech
- Of, or relating to these creatures