Grind away in bar in central Greece? (5)
I believe the answer is:
erode
'grind away' is the definition.
(I've seen this in another clue)
'bar in central greece' is the wordplay.
'bar' becomes 'rod' (both can mean a pole or stick).
'in' indicates putting letters inside.
'central' indicates the central letters.
The centre of 'greece' is 'ee'.
'rod' going inside 'ee' is 'ERODE'.
'in' is the link.
(Other definitions for erode that I've seen before include "Wear away with weather" , "fragment" , "Grind down" , "Abrade" , "Corrode" .)