Grooves rust away (4)
I believe the answer is:
ruts
'grooves' is the definition.
(I know this)
'rust away' is the wordplay.
'away' indicates an anagram (letters move away from their original places).
'rust' anagrammed gives 'RUTS'.
(Other definitions for ruts that I've seen before include "Deep tracks in paths" , "gets ready for new partner" , "Deep tracks in path" , "Deep furrows" , "Furrows not to get stuck in" .)