In a month we go for workers’ supplement (7)
I believe the answer is:
augment
'supplement' is the definition.
(I've seen this before)
I don't understand the rest of the clue.
Can you help me to learn more?
(Other definitions for augment that I've seen before include "Expand" , "Make greater in size, number, etc." , "Add to, increase" , "get longer" , "Increase number of" .)