Works up to employ a partner (6)
I believe the answer is:
spouse
'a partner' is the definition.
('spouse' can be a synonym of 'partner')
'works up to employ' is the wordplay.
'works' becomes 'ops' (I've seen this in other clues).
'up' says the letters should be written backwards (in down clue: letters go upwards).
'to employ' becomes 'use' ('use' can be a synonym of 'employ').
'ops' back-to-front is 'spo'.
'spo'+'use'='SPOUSE'
(Other definitions for spouse that I've seen before include "mate" , "old lady?" , "Partner in marriage" , "Consort" , "Possibly wife" .)