Bird found in Eastern estuaries (5)
I believe the answer is:
ernes
'bird found' is the definition.
I can't judge whether this definition defines the answer.
'in eastern estuaries' is the wordplay.
'in' indicates the answer is hidden within the clue.
'ERNES' is hidden within 'eastern estuaries'.
Can you help me to learn more?
(Other definitions for ernes that I've seen before include "They fly across the sea" , "sea eagles" , "Sea-eagles" , "Certain birds" , "Irish lough's" .)