Criticise innocent person, a saint (7)

I believe the answer is:

lambast

'criticise' is the definition.
(I know that lambast is a more specific form of the action criticise)

'innocent person a saint' is the wordplay.
'innocent person' becomes 'lamb' (I've seen this in other clues).
'saint' becomes 'st' (abbreviation).
'lamb'+'a'+'st'='LAMBAST'

(Other definitions for lambast that I've seen before include "Harshly criticise" , "Roast" , "Be harsh critic of" , "Reprimand" , "Criticise severely" .)

I've seen this clue in The Times.

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