Diagnostic machine useful in the office (7)
I believe the answer is:
scanner
This clue is a double definition.
'diagnostic machine' is the first definition.
'useful in the office' is the second definition.
(Other definitions for scanner that I've seen before include "Digitiser; hospital machine" , "Document converter" , "Doccument copier" , "Imaging and reproductive device" , "Device used to help medical diagnosis" .)