Nice bloke's casual wear (5)

I believe the answer is:

jeans

'casual wear' is the definition.

I don't understand how the remainder of the clue works.

(Other definitions for jeans that I've seen before include "Trousers made of strong cotton, usually dyed blue" , "Denim trousers" , "(Usually) blue casual wear" , "article of clothing" , "Casual trousers, sometimes stonewashed?" .)

I've seen this clue in The Guardian.

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