Genuflecting joint (4)
I believe the answer is:
knee
'genuflecting joint' is the definition.
(I've seen this in another clue)
This is all the clue.
(Other definitions for knee that I've seen before include "one is bent on submission" , "Hinge joint" , "proposal might be made on one" , "Technical name for this joint is genu" , "joint input" .)