Architect, one into dreadful jingoism mostly (5,5)

I believe the answer is:

inigo jones

'architect' is the definition.

'one into dreadful jingoism mostly' is the wordplay.
'into' indicates putting letters inside.
'dreadful' indicates an anagram.
'mostly' means to remove the last letter.
'jingoism' with its last letter removed is 'jingois'.
'jingois' anagrammed gives 'inigojs'.
'one' placed within 'inigojs' is 'INIGO JONES'.

I've seen this clue in The Independent.

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