Fishy contribution from Schubert (4)

I believe the answer is:

chub

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'fishy contribution' is the definition.
Although both the answer and definition are singular nouns, I don't see how they can define each other.

'from schubert' is the wordplay.
'from' indicates a hidden word.
'CHUB' is hidden in the letters of 'schubert'.

Can you help me to learn more?

(Other definitions for chub that I've seen before include "River fish; rhymes with public house" , "Fat relative of the carp" , "Thick-bodied river fish" , "European freshwater fish" , "Small river fish of the carp family" .)

I've seen this clue in the Evening Standard.

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