The season's quickly over and is not up to expectations (5,5)

I believe the answer is:

falls short

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'and is not up to expectations' is the definition.
I know nothing about this answer so I cannot tell whether this works.

'the season's quickly' is the wordplay.
'the season's' becomes 'falls' (alternative name for autumn).
'quickly' becomes 'short' (I am not sure about this - if you are sure you should give a lot more credence to this answer).
'falls'+'short'='FALLS SHORT'

'over' is the link.

Can you help me to learn more?

I've seen this clue in the Evening Standard.

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