Joint head of kindergarten born in Marseille (4)
I believe the answer is:
knee
'joint' is the definition.
(knee joint is a kind of joint)
'head of kindergarten born in marseille' is the wordplay.
'head of' suggests taking the first letters.
'born in marseille' becomes 'nee' (I can't justify this - if you can you should believe this answer much more).
The initial letter of 'kindergarten' is 'k'.
'k'+'nee'='KNEE'
Can you help me to learn more?
(Other definitions for knee that I've seen before include "Thigh/shin connector" , "Technical name for this joint is genu" , "Hinge between the thigh and the shin" , "one is bent on submission" , "One bent in genuflection" .)