Attack a seaman, we hear (7)

I believe the answer is:

assault

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'attack' is the definition.
(I know that attack can be written as assault)

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

Can you help me to learn more?

(Other definitions for assault that I've seen before include "Onslaught" , "Physical attack" , "Mount an attack" , "set about" , "Sort of course" .)

I've seen this clue in The Irish Independent.

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