Renal organ (6)
I believe the answer is:
kidney
'renal organ' is the definition.
(I've seen this before)
This is all the clue.
(Other definitions for kidney that I've seen before include "Glandular organ that removes waste matter from blood" , "Bean-shaped organ" , "Organ; kind; bean type" , "Organ associated with steak" , "Excretory organ" .)