Flipping costly keeping sailors in drink (3-5)

I believe the answer is:

rat-arsed

'in drink' is the definition.
(UK slang for very drunk)

'flipping costly keeping sailors' is the wordplay.
'flipping' shows that the letters should be reversed in order.
'costly' becomes 'dear' ('dear' can be a synonym of 'costly').
'keeping' indicates putting letters inside.
'sailors' becomes 'tars' (tar is a kind of sailor).
'dear' backwards is 'raed'.
'raed' enclosing 'tars' is 'RAT-ARSED'.

I've seen this clue in The Guardian.

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