Large eared seal (3,4)
I believe the answer is:
sea lion
'large eared seal' is the definition.
(I've seen this in another clue)
This is all the clue.
(Other definitions for sea lion that I've seen before include "Is alone (anag.)" , "Large marine mammal" , "one often immersed in salty water" , "Large seal" , "Large-eared mammal of Pacific Ocean, like Leo" .)