Dreary routine produces depression (3)
I believe the answer is:
rut
I believe this clue is a double definition.
'dreary routine' is the first definition.
(I've seen this before)
'depression' is the second definition.
(I know that rut is a type of channel)
'produces' is the link.
(Other definitions for rut that I've seen before include "Groove worn by wheels" , "Groove or furrow - don't get into one" , "Furrow left by wheel" , "Dull routine behaviour" , "have sex!" .)