Put one over seabird (4)

I believe the answer is:

gull

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'seabird' is the definition.
(seagull)

I don't understand how the rest of the clue works.

(Other definitions for gull that I've seen before include "Seabird - fool" , "Common seabird" , "Rook - bird of the sea" , "Mostly white aquatic bird" , "Fool - bird" .)

I've seen this clue in the Sydney Morning Herald.

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