The phrase "a really obvious" is correct and usable in written English.
It can be used to emphasize that something is clear or easily understood.
Example: "The solution to the problem was a really obvious choice for everyone involved."
Alternatives: "a very clear" or "an extremely evident".
And my dad was a really obvious one, because we had a faltering relationship all my life.
"A really obvious example of what we're looking out for: including a version of OpenSSL that's an old version.
Shazam became a really obvious user experience [after the app came out]." Like many businesses, Shazam was conceived by two friends kicking around lofty ideas.
At first I was a little disappointed as the narrative seemed to allude to a really obvious resolution to the crimes that Charley witnessed.
Sometimes I wonder whether I'd have challenged him if he had he told me a really obvious and scary lie, like 'I've killed dozens of people'.
"In fairness to the police, there's been a really obvious presence and the determination to find her has been really obvious.
As for why their announcement was so quickly followed by two similar apps, they are a bit clearer: "It's a really, really obvious joke.
Not least on the minds of the president or any would-be commander in chief, he added, was that to do nothing "hands the opposition a bunch of really obvious talking points".
They make a lot of really obvious jokes about, "What's next?
"We have plenty of experience in dealing with people who try to spin Wikipedia - after a while it becomes really obvious". He said that Wikipedia would be reviewing the effectiveness of its system for flagging up suspicious additions or edits.
When you're at a show, it's really obvious that the audience is the show.
