Deep groove (3)
I believe the answer is:
rut
'deep groove' is the definition.
(I've seen this in another clue)
This is all the clue.
(Other definitions for rut that I've seen before include "A worn groove - don't live in one" , "Groove worn in surface" , "excitement in male deer" , "Boring groove to be stuck in!" , "does get followed during this" .)