Midleg (4)
I believe the answer is:
knee
'midleg' 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 "proposal might be made on one" , "It jerks reactively" , "may present problem to maid" , "Genuflector?" , "Where the femur meets the tibia" .)