Opportunist not unknown in court (7)

I believe the answer is:

chancer

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'opportunist' is the definition.
(I've seen this before)

I cannot understand how the remainder of the clue works.

(Other definitions for chancer that I've seen before include "opportunistic sort" , "One taking risks" , "Exploiter of opportunity" , "Unscrupulous opportunist" , "Unscrupulous sort" .)

I've seen this clue in The Times.

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