Easy to see or understand (7)
(Other definitions for obvious that I've seen before include "Clear; easy to see" , "Quite evident, manifest" , "Easily perceived or understood" , "Not subtle" , "Evident, plain" .)
'easy to see or understand' is the definition.
(I've seen this before)
This is all the clue.
(Other definitions for clear that I've seen before include "Pellucid" , "With no jams" , "Plainly" , "Easily understood" , "Open; not cloudy" .)