Writer attached to China as correspondent (3,3)
I believe the answer is:
pen pal
'correspondent' is the definition.
(pen pal is a kind of correspondent)
'writer attached to china' is the wordplay.
'writer' becomes 'pen' (something which writes).
'attached to' says to put letters next to each other.
'china' becomes 'pal' (china plate is Cockney rhyming slang for mate).
'pen'+'pal'='PEN-PAL'
'as' is the link.
(Other definitions for pen pal that I've seen before include "Mail friend" , "American friend via correspondence" , "Regular overseas correspondent" , "A friend who communicates through correspondence" , "A friendly correspondent" .)