Ankle-knee connector (4)
I believe the answer is:
shin
'ankle-knee connector' is the definition.
(I've seen this in another clue)
This is all the clue.
(Other definitions for shin that I've seen before include "kick" , "Front part of the leg between knee and ankle" , "Lower foreleg" , "Cut of beef; part of leg" , "Front end of the tibia" .)