Crossword Genius

Marine mammal, close (4)

Ross

I believe the answer is:

seal

I believe this clue is a double definition.

'marine mammal' is the first definition.
(I've seen this before)

'close' is the second definition.
(sealing is a kind of closing)

(Other definitions for seal that I've seen before include "Imprinted disk affixed to a document" , "Member of an elite force within the US Navy" , "Make tight" , "Authorise - plug" , "marine creature" .)

I've seen this clue in The Times.
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