Tied up, in case ale drunk (6)

I believe the answer is:

sealed

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'tied up' is the definition.
Both the definition and answer are adjectives. Perhaps there's an association between them I don't understand?

'in case ale drunk' is the wordplay.
'in' says the answer is hidden in the clue.
'SEALED' can be found hidden inside 'case ale drunk'.

Can you help me to learn more?

(Other definitions for sealed that I've seen before include "Closed (of lips, envelope, tomb etc)" , "Stamped as authentic" , "Secured against leakage" , "Fastened as in S.W.A.L.K." , "Securely fastened" .)

I've seen this clue in The Independent.

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