A critic of the legal system? (5)

I believe the answer is:

judge

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'a critic' is the definition.
(thesaurus)

I don't understand the remainder of the clue.

(Other definitions for judge that I've seen before include "Estimate" , "Arbitrate" , "Arbitrator" , "Form an opinion of" , "Assess" .)

I've seen this clue in the Evening Standard.

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