Ones who admit having joint possession (9)
I believe the answer is:
ownership
'possession' is the definition.
('ownership' can be a synonym of 'possession')
'ones who admit having joint' is the wordplay.
I cannot really understand how this works, but
'admit' could be 'own' (I've seen this before) and 'own' is found within the answer.
'joint' could be 'hip' (hip is a kind of joint) and 'hip' is found within the answer.
The remaining letters 'ers' is a valid word which might be clued in a way I don't understand.
This may be the basis of clue (or it may be nonsense).
Can you help me to learn more?
(Other definitions for ownership that I've seen before include "Legal title" , "The right of possessing something" , "Proprietorship, possession" , "Proprietary right of possession" .)