A striped design is most quick (8)

I believe the answer is:

rapidest

'most quick' is the definition.
('rapid' can be a synonym of 'quick')

'a striped design' is the wordplay.
'design' indicates an anagram.
'a'+'striped'='astriped'
'astriped' is an anagram of 'RAPIDEST'.

'is' is the link.

(Another definition for rapidest that I've seen is " Most speedy".)

I've seen this clue in The Daily Express.

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