Super fish (5)
I believe the answer is:
brill
This might be a double definition.
'super' is the first definition.
Although both the answer and definition are singular nouns, I can't see how they can define each other.
'fish' is the second definition.
(brill is a kind of fish)
Can you help me to learn more?
(Other definitions for brill that I've seen before include "Very good - fish" , "Champion" , "Excellent (abbr) - fish" , "Fab -- fish" , "catch, perhaps" .)