Freshwater duck with a red back (4)

I believe the answer is:

oder

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'freshwater duck with a red back' is the definition.
I can't judge whether this defines the answer.

'duck with a red back' is the wordplay.
'duck' becomes 'o' (resembles zero - 'duck' in cricket).
'with' is a charade indicator (letters next to each other).
'back' is a reversal indicator.
'red' back-to-front is 'der'.
'o'+'der'='ODER'

Can you help me to learn more?

(Other definitions for oder that I've seen before include "waterway" , "Polish/German river" , "European flower" , "German banker" , "German river that empties into the Baltic Sea" .)

I've seen this clue in the Evening Standard.

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