Now recants? An amazingly ineffective (and costly) method of crowd control (5,7)

I believe the answer is:

water cannons

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'ineffective and costly method of crowd control' is the definition.
I know nothing about this answer so I cannot judge whether this works.

'now recants? an amazingly' is the wordplay.
'amazingly' is an anagram indicator.
'now'+'recants'+'an'='nowrecantsan'
'nowrecantsan' anagrammed gives 'WATER-CANNONS'.

Can you help me to learn more?

I've seen this clue in The Independent.

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