Grinding implement (6)
I believe the answer is:
pestle
'grinding implement' is the definition.
(I've seen this in another clue)
This is the entire clue.
(Other definitions for pestle that I've seen before include "Partner to the mortar" , "Small club for use with mortar" , "Grinder for mortar" , "Tool for pounding or grinding" , "A grinder or pounder" .)