Nudging joint (5)
I believe the answer is:
elbow
'nudging joint' is the definition.
(I've seen this in another clue)
This is all the clue.
(Other definitions for elbow that I've seen before include "Arm joint, more power to it" , "Sort of grease" , "Sharp bend in a road or river" , "Below (anag.)" , "part of the body" .)