Exercise device: dull routine (9)
I believe the answer is:
treadmill
I believe this clue is a double definition.
'exercise device' is the first definition.
(I've seen this in another clue)
'dull routine' is the second definition.
(I've seen this before)
(Other definitions for treadmill that I've seen before include "Tiresome job" , "tedious routine" , "tedious work" , "Boring or unending job" , "Situation of routine drudgery" .)