State supporting China in discussion (7)
I believe the answer is:
palaver
'discussion' is the definition.
(palaver can mean a discussion or conference)
'state supporting china' is the wordplay.
I cannot really understand how this works, but
'state' could be 'aver' (both can mean to declare) and 'aver' is found in the answer.
'china' could be 'pal' (china plate is Cockney rhyming slang for mate) and 'pal' is located in the answer.
No letters remain.
This explanation may well be incorrect...
'in' acts as a link.
(Other definitions for palaver that I've seen before include "Prolonged fuss" , "Time-consuming business" , "Fuss and bother" , "Long tedious fuss" , "Kind of discussion or idle chatter" .)