Law courts denounce war on unruly grasshopper (6)

I believe the answer is:

locust

I'm a little stuck... Click here to teach me more about this clue!

'grasshopper' is the definition.
(I know that locust is a type of acridid)

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

Can you help me to learn more?

(Other definitions for locust that I've seen before include "beast resulting in destruction" , "A deadly grasshopper seen in plagues" , "Voracious insect, travels in swarms" , "Destructive tropical grasshopper" , "plaguey type" .)

I've seen this clue in The Irish Times.

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