Uneducated (8)
I believe the answer is:
ignorant
'uneducated' is the definition.
(similar in meaning)
This is all the clue.
(Other definitions for ignorant that I've seen before include "No rating (anag) - in the dark" , "Ill-educated" , "Lacking in or good manners" , "Discourteous" , "Poorly-educated" .)