Country history's unwritten (8)
I believe the answer is:
pastoral
'country' is the definition.
(thesaurus)
'history's unwritten' is the wordplay.
'history' becomes 'past' (I've seen this before).
'unwritten' becomes 'oral' ('oral' can be a synonym of 'unwritten').
'past'+'oral'='PASTORAL'
(Other definitions for pastoral that I've seen before include "Relating to rural life" , "(Poem) of country life" , "Of shepherds or spiritual guides" , "Beethoven's 6th symphony ..." , "of minister's duties" .)