How much has leaked from hateful lager? (6)

I believe the answer is:

ullage

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'how much has leaked' is the definition.
I can't judge whether this defines the answer.

'from hateful lager?' is the wordplay.
'from' says the answer is hidden in the clue.
'ULLAGE' is hidden within 'hateful lager'.

Can you help me to learn more?

(Other definitions for ullage that I've seen before include "dregs" , "Amount by which a liquid container falls short of being full" , "shortfall" , "Loss by evaporation or leakage" , "The amount by which a bottle falls short of being full" .)

I've seen this clue in The Daily Mail.

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