The phrase "an indication why" is correct and usable in written English.
It can be used when you want to express a reason or explanation for something.
Example: "The report provided an indication why the project failed to meet its deadlines."
Alternatives: "a reason for" or "an explanation for".
Soon Cook was soon giving an indication why: "We batted better, we bowled better and we fielded better".
The winger's first touch gave an indication why - after mis-controlling the ball he ran to retrieve it but instead headed it straight out of play.
Still, crowding has been a problem; the arrest in October of the village's building inspector on charges of selling false driver's licenses to illegal immigrants gives an indication why.
It also gives the viewer an indication why the other members of Genesis might have begun to resent the growing impression that they were merely a backup group for their charismatic lead singer.
Google has always been pretty cagey about the financials behind its Android mobile OS — and data that has emerged over the last week could give us an indication why: it's been losing money from Day One.
It's an indication why college is a fairly clear sell for younger people.
After much trial and error, I have learned to include any and all possible controls in my assays, to appreciate the silence of cell cultures (compared to hospital patients), and to not get too discouraged when experiments do not yield the expected results for the third time in a row without any indication why.
But it offers neither specifics nor any indication why returning to George W. Bush's policies would cure a slump that began on Mr. Bush's watch.
"When you disappear into the ether without any indication why, all I can do is come up with a million and a half reasons why you're not into me," she wrote.
If there was any indication why that kind of diversification was important, you can look to the second quarter this year — when Alphabet, for a split second, became the most valuable company in the world and surpassed Apple.
Later, after the brief 20-minute opening ceremony, he called the moment "bittersweet" and gave a good indication why.
