This joint, mostly twisted, would lead to wail (4)
I believe the answer is:
knee
'this joint' is the definition.
(knee joint is a kind of joint)
I can't explain the remainder of the clue.
(Other definitions for knee that I've seen before include "Leg?joint" , "Where the femur meets the tibia" , "Lower limb joint" , "Flexible joint" , "Hinge between the thigh and the shin" .)