Futuristic radical fashion by navy (11)

I believe the answer is:

ultramodern

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'futuristic' is the definition.
Although both the answer and definition are adjectives, I cannot see how one could define the other.

'radical fashion by navy' is the wordplay.
'radical' becomes 'ultra' (synonyms).
'fashion by' becomes 'mode' (synonyms. I am not sure about the 'by' bit.).
'navy' becomes 'RN' (abbreviation for Royal Navy).
'ultra'+'mode'+'rn'='ULTRAMODERN'

Can you help me to learn more?

(Other definitions for ultramodern that I've seen before include "up-to-date? Certainly" , "avant-garde" , "New" .)

I've seen this clue in The Daily Express.

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