Prisoner in China (6)
I believe the answer is:
inmate
'prisoner' is the definition.
(inmate can mean someone in prison)
'in china' is the wordplay.
'china' becomes 'mate' (china plate is Cockney rhyming slang for mate).
'in'+'mate'='INMATE'
(Other definitions for inmate that I've seen before include "Con" , "eg Prisoner" , "One institutionally confined" , "Occupant" , "One in prison/hospital" .)