Work's returning; employ a partner (6)
I believe the answer is:
spouse
'a partner' is the definition.
(I know that partner can be written as spouse)
'work's returning employ' is the wordplay.
'work's' becomes 'op's' (abbreviation for opus).
'returning' says the letters should be written in reverse.
'employ' becomes 'use' (synonyms).
'ops' backwards is 'spo'.
'spo'+'use'='SPOUSE'
(Other definitions for spouse that I've seen before include "mate" , "Elizabethan dance" , "Husband or wife" , "Very hot and dry" , "Other half" .)