Acknowledgement that may be jolly? (5)

I believe the answer is:

roger

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'jolly?' is the definition.
Both the answer and definition are verbs in their base form.
Perhaps they are linked in a way I don't understand?

I don't understand the remainder of the clue.

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(Other definitions for roger that I've seen before include "Boy's name - message understood" , "Received (in radio comms)" , "Sir - de Coverley, English country dance" , "... guy" , "Radio acknowledgment" .)

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