Barking beast (4)
I believe the answer is:
seal
'barking beast' is the definition.
(I've seen this in another clue)
This is all the clue.
(Other definitions for seal that I've seen before include "Sea-dweller can produce a wax impression" , "Fasten securely; aquatic mammal" , "Stamp of guarantee" , "Bull or cow" , "marine creature" .)