They will admit joint possession? (9)
I believe the answer is:
ownership
'possession?' is the definition.
(I know that possession can be written as ownership)
'they will admit joint' is the wordplay.
I cannot quite understand how this works, but
'admit' could be 'own' (own can mean to admit or acknowledge) and 'own' is present in the answer.
'joint' could be 'ship' (I've seen this in other clues) and 'ship' is present in the answer.
The remaining letters 'er' is a valid word which might be clued in a way I don't understand.
This may be the basis of the clue (or it may be nonsense).
Can you help me to learn more?
(Other definitions for ownership that I've seen before include "Proprietorship, possession" , "Proprietary right of possession" , "The right of possessing something" , "Legal title" .)