Fish in the band? (9)
I believe the answer is:
trumpeter
'fish in the band?' is the definition.
The answer and definition can be both animals as well as being singular nouns.
Perhaps they are linked in a way I don't understand?
This is all the clue.
Can you help me to learn more?
(Other definitions for trumpeter that I've seen before include "Perhaps Nellie" , "Jumbo?" , "One touting own skills perhaps" , "Instrumentalist - type of swan" , "Elephant perhaps" .)