Steady, dull and laborious routine (5)
![Ross](/clue/static/ross-mug.min.png)
I believe the answer is:
grind
(Other definitions for grind that I've seen before include "Put through the mill" , "Hard work, as in mill" , "Abrade - laborious task" , "Crush, oppress; hard work" , "Harshly rub together" .)