Birds that honk (5)
I believe the answer is:
geese
'birds that honk' is the definition.
(I've seen this in another clue)
This is all the clue.
(Other definitions for geese that I've seen before include "Water birds related to ducks and swans" , "Christmas birds" , "Large birds of the duck family" , "Sixth day of Christmas gift" , "Domesticated fowl" .)