Being critical of second boozer's action (8,4)

I believe the answer is:

knocking back

'boozer's action' is the definition.
(knocking back drinks)

'being critical of second' is the wordplay.
'being critical of' becomes 'knocking' (knock can mean to criticise).
'second' becomes 'back' (to second a motion is to back it).
'knocking'+'back'='KNOCKING BACK'

I've seen this clue in The Times.

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