Hopefully learning many are involved in this legal matter (5,6)

I believe the answer is:

class action

'many are involved in this legal matter' is the definition.
(a class action is a lawsuit filed by a group)

I don't understand how the remainder of the clue works.

(Another definition for class action that I've seen is " This is the case for a lot of people".)

I've seen this clue in The Times.

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