Ready to be received outside working hours? (4,3)

I believe the answer is:

sick pay

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'received outside working hours?' is the definition.
Although both the answer and definition are singular nouns, I don't understand how they can define each other.

'ready to be' is the wordplay.
'ready to' becomes 'sick' (I am not sure about this - if you are sure you should give a lot more credence to this answer).
'be' becomes 'pay' (paying is a kind of being).
'sick'+'pay'='SICK PAY'

Can you help me to learn more?

I've seen this clue in The Telegraph.

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