whizzkid
From Longman Dictionary of Contemporary Englishwhizzkidwhizz‧kid British English, whiz kid American English /ˈwɪzkɪd/ noun [countable] informal INTELLIGENTa young person who is very skilled or successful at something financial whizzkids in the CityExamples from the Corpuswhizzkid• Wittgenstein was a whizzkid who wanted to be an aviator and ended up teaching philosophy at Cambridge from a green deck chair.