Tool used with a mortar (6)
I believe the answer is:
pestle
'tool used with a mortar' is the definition.
(I've seen this before)
This is the entire clue.
(Other definitions for pestle that I've seen before include "Instrument for pounding spices etc" , "Small club, goes with mortar" , "Partner to the mortar" , "found at pound shop?" , "Kitchen item" .)