Joints below the head in bugs (6)
I believe the answer is:
ankles
'joints' is the definition.
(ankle is a kind of joint)
I don't understand the rest of the clue.
Can you help me to learn more?
(Other definitions for ankles that I've seen before include "Between legs and feet" , "Body joints" , "Low joints" , "Major foot joints" , "Leg joints" .)