Hawaiian goose (4)
I believe the answer is:
nene
'hawaiian goose' is the definition.
(I've seen this in another clue)
This is the entire clue.
(Other definitions for nene that I've seen before include "River navigable to Northampton" , "Hawaiian goose; English river" , "Rare bird" , "Peterborough's river" , "Northants river" .)