A rewarding occasion (6)

I believe the answer is:

payday

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'a rewarding occasion' is the definition.
Although both the answer and definition are singular nouns, I don't understand how one could define the other.

This is the entire clue.

Can you help me to learn more?

(Other definitions for payday that I've seen before include "Time when wages are received" , "when wages are given" .)

I've seen this clue in the Evening Standard.

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