Small duck found in northern Eurasia, which nests in tree holes (4)
I believe the answer is:
smew
(Other definitions for smew that I've seen before include "Bird" , "Species of merganser" , "Small merganser" , "Sea duck" , "Diver" .)
I believe the answer is:
smew
(Other definitions for smew that I've seen before include "Bird" , "Species of merganser" , "Small merganser" , "Sea duck" , "Diver" .)