A fixed, regular payment for work (6)
I believe the answer is:
salary
'a fixed regular payment for work' is the definition.
(I've seen this before)
This is all the clue.
(Other definitions for salary that I've seen before include "(Employee's) pay" , "Stipend" , "Remuneration for Ray and Sal" , "Employee's remuneration" , "Regular income from employment" .)