to know about sth or be in a situation that could lead to a good result for you :
Scientists believe they are onto something big.
She's onto a good thing with that new job.
to know about sth or be in a situation that could lead to a good result for you :
Scientists believe they are onto something big.
She's onto a good thing with that new job.
Oxford Advanced Learner's English Dictionary. Оксфордский английский словарь для изучающик язык на продвинутом уровне. 2005