bright young thing 
noun
An enthusiastic, ambitious, and self-consciously fashionable young person, a term originally applied in the 1920s to a member of a young fashionable set noted for exuberant and outrageous behaviour: his mansion in Los Angeles was a magnet for the bright young things of Hollywood...
- The bright young things behind the bar are clearly still befuddled by the complicated computer tills.
- The event will see the designer giving advice to those bright young things who want to follow in his footsteps.
- Alongside their real life stories we'll discover if today's bright young things can do it - old style.