After you season in preparation for dish (3,6,6)

I believe the answer is:

age before beauty

'after you' is the definition.
(both might be said to let someone else to go first)

'season in preparation for dish' is the wordplay.
'season' becomes 'age'.
'in preparation for' becomes 'before' (both can mean 'in anticipation of').
'dish' becomes 'beauty' (dish can mean an attractive person).
'age'+'before'+'beauty'='AGE BEFORE BEAUTY'

I've seen this clue in The Guardian.

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