A bird called Ida (5)
I believe the answer is:
eider
'a bird' is the definition.
(eider is a kind of bird)
I cannot understand how the remainder of the clue works.
Can you help me to learn more?
(Other definitions for eider that I've seen before include "Duck valued for its fine soft down" , "Down-producing duck" , "ie Red (anag.)" , "Variety of duck" , "Reed I turn into a duck" .)