First border described by China (6)
I believe the answer is:
primal
'first' is the definition.
(primal can mean early or first)
'border described by china' is the wordplay.
'border' becomes 'rim' (both can mean an edge).
'described by' indicates putting letters inside (to describe can mean to form an outline).
'china' becomes 'pal' (china plate is Cockney rhyming slang for mate).
'rim' placed within 'pal' is 'PRIMAL'.
(Other definitions for primal that I've seen before include "Original, fundamental" , "Primeval, original" , "Sort of scream" , "Existing from the beginning, basic" , "Relating to an early stage of evolution" .)