How a tailor might make the grade? (7,2)

I believe the answer is:

measure up

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'make the grade?' is the definition.
(I've seen this in another clue)

I cannot understand how the remainder of the clue works.

Can you help me to learn more?

(Other definitions for measure up that I've seen before include "Reach required standard" , "Have what it takes" , "adequate for the job?" , "Reach the expected standard" , "Pass" .)

I've seen this clue in The Guardian.

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