Obvious, plain (8)
I believe the answer is:
manifest
I believe this clue is a double definition.
'obvious' is the first definition.
(similar in meaning)
'plain' is the second definition.
(synonyms)
(Other definitions for manifest that I've seen before include "(Of ghost) appear" , "Customs document listing contents of ship or plane" , "Document listing a ship's contents for customs purposes" , "Reveal" , "list of passengers for customs" .)