Partners welcome a good salary (4)
I believe the answer is:
wage
'salary' is the definition.
('wage' can be a synonym of 'salary')
'partners welcome a good' is the wordplay.
'partners' becomes 'we'.
'welcome' means one lot of letters goes inside another (in sense of 'inviting in').
'a good' becomes 'ag' (I've seen this in other clues**).
'we' enclosing 'ag' is 'WAGE'.
(Other definitions for wage that I've seen before include "Regular amount of income" , "Regular money for work" , "Pursue" , "conduct" , "Money earned" .)