Diagnostic device useful in the office (7)

I believe the answer is:

scanner

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'useful in the office' is the definition.

I can't explain the rest of the clue.

(Other definitions for scanner that I've seen before include "Medical camera" , "Document digitiser" , "Device used to help medical diagnosis" , "Imaging and reproductive device" , "Imaging machine" .)

I've seen this clue in The Mirror.

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