Certain Americans developing British mania, alas (10)

I believe the answer is:

alabamians

'certain americans' is the definition.
(people from Alabama)

'developing british mania alas' is the wordplay.
'developing' is an anagram indicator (letters developed into a new form).
'british' becomes 'b' (abbreviation e.g. in 'BBC').
'b'+'mania'+'alas'='bmaniaalas'
'bmaniaalas' anagrammed gives 'ALABAMIANS'.

I've seen this clue in The Times.

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