Monotonous, but it could be considered groovy (3)
I believe the answer is:
rut
'it could be considered groovy' is the definition.
The definition suggests a singular noun which matches the answer.
I don't understand how the rest of the clue works.
Can you help me to learn more?
(Other definitions for rut that I've seen before include "hazard in the road" , "Monotony that's hard to escape" , "It can be frustrating" , "predictable course" , "Deep track or dull routine" .)