Pickled food given a once-over (3,4)

I believe the answer is:

pie eyed

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'pickled' is the definition.
(thesaurus)

'food given a once-over' is the wordplay.
'food' becomes 'pie' (pie is a kind of food).
'given a once-over' becomes 'eyed' (I can't explain this - if you can you should give a lot more credence to this answer).
'pie'+'eyed'='PIE-EYED'

Can you help me to learn more?

(Another definition for pie eyed that I've seen is " Drunk".)

I've seen this clue in The Daily Express.

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