Mind china for bosom buddy (4,4)
I believe the answer is:
soul mate
'mind' is the definition.
The definition and answer can be both people as well as being singular nouns.
Perhaps there's an association between them I don't understand?
'china for bosom buddy' is the wordplay.
'china' becomes 'mate' (china plate is Cockney rhyming slang for mate).
'for' is a charade indicator (letters next to each other) (I've seen this in other clues).
'bosom buddy' becomes 'soul' (I can't explain this - if you can you should give a lot more credence to this answer).
'mate' after 'soul' is 'SOUL MATE'.
Can you help me to learn more?
(Other definitions for soul mate that I've seen before include "Friend with a deeply personal relationship, like spiritual spouse" , "lover?" , "One ideally suited to another" , "Person ideally suited to another" , "Person sharing deep affinity" .)