Barking mammal (4)
I believe the answer is:
seal
'barking mammal' is the definition.
(I've seen this in another clue)
This is the entire clue.
(Other definitions for seal that I've seen before include "Fasten with hot wax" , "Wax stamp" , "Amphibious mammal or stamp of authenticity" , "Sea beast - authenticating mark" , "Sea mammal in sale" .)