Factions riot -- if worried, we need these? (14)

I believe the answer is:

fortifications

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'we need these?' is the definition.
The definition suggests an adverb but the answer is not.

'factions riot if worried' is the wordplay.
'worried' indicates an anagram (worry can mean to interfere with or disturb).
'factions'+'riot'+'if'='factionsriotif'
'factionsriotif' anagrammed gives 'FORTIFICATIONS'.

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I've seen this clue in The Telegraph.

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