It may form a strong attachment to a craft (8)

I believe the answer is:

barnacle

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'it may form a strong attachment to a craft' is the definition.
The definition suggests a singular noun which matches the answer.

This is all the clue.

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(Other definitions for barnacle that I've seen before include "Sea creature - lean crab (anag)" , "A shellfish that sticks to objects under water" , "hanger-on" , "underwater attachment" , "Crustacean that attaches to underwater surfaces" .)

I've seen this clue in The Irish Independent and The Globe and Mail.

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