Paper factory (4)
I believe the answer is:
mill
'paper factory' is the definition.
(I've seen this in another clue)
This is the entire clue.
(Other definitions for mill that I've seen before include "There's an old one by the stream, Nellie Dean" , "Where work is a grind" , "No fun going through this" , "Plant with facilities for manufacturing" , "(Pepper) grinder" .)