Making a siren go off in certain areas (7)

I believe the answer is:

regions

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'off in certain areas' is the definition.
'regions' can be an answer for 'areas' ('region' can be a synonym of 'area'). I am not certain of the 'off in certain' bit.

'making a siren go' is the wordplay.
'making' is an anagram indicator.
'siren'+'go'='sirengo'
'sirengo' anagrammed gives 'REGIONS'.

Can you help me to learn more?

(Other definitions for regions that I've seen before include "patches" , "'Areas, locations (7)'" , "Parts of the country" , "Ignores (anag.)" , "Domains" .)

I've seen this clue in the Evening Standard.

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