Animal is close (4)
I believe the answer is:
seal
I believe this is a double definition.
'animal' is the first definition.
(I have seen 'Marine animal' mean 'seal' so perhaps 'animal' could also mean 'seal')
'is close' is the second definition.
(I've seen this in another clue)
(Other definitions for seal that I've seen before include "relative of the walrus" , "Amphibious sea animal or kind of stamp" , "Secure against leakage" , "Make waterproof - stamp" , "Close up - marine mammal" .)