Exercise in reordering of trousers in large shop (10)

I believe the answer is:

superstore

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'exercise in reordering of trousers in large shop' is the definition.
'superstore' can be an answer for 'shop' (I've seen this before). I am not certain of the 'exercise in reordering of trousers in large' bit.

'large shop' is the wordplay.
'large' becomes 'super' (similar in meaning).
'shop' becomes 'store' (synonyms).
'super'+'store'='SUPERSTORE'

Can you help me to learn more?

(Other definitions for superstore that I've seen before include "Retailer" , "Large out-of-town shop" .)

I've seen this clue in The Times.

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