Navy bird? (4)
I believe the answer is:
This clue might be a double definition.
'navy' is the first definition.
Although both the answer and definition are singular nouns, I don't see how one could define the other.
'bird?' is the second definition.
(I know that wren is a type of passeriform bird)
Can you help me to learn more?
(Other definitions for wren that I've seen before include "held up by wings at small scale?" , "Small active brown northern hemisphere bird" , "Former RN woman" , "Tiny brown songbird with a short upright tail" , "A songster" .)