… in upholding the employee’s originally overturned case (4)
I believe the answer is:
etui
'case' is the definition.
(I've seen this before)
'in upholding the employee's originally overturned' is the wordplay.
'originally' indicates taking the first letters.
'overturned' says the letters should be written in reverse.
The first letters of 'in upholding the employees' is 'iute'.
'iute' reversed gives 'ETUI'.
(Other definitions for etui that I've seen before include "box" , "Needlework case" , "Small ornamental case" , "Sewer's case" , "Tiny ladies' bag" .)