Wiktionary
up-and-comer
n. (context idiomatic English) someone who is up-and-coming, who has begun to be successful in some field and is likely to become even more successful in the future
Usage examples of "up-and-comer".
When he'd first set eyes on his interrogator, McGregor pegged him for some young up-and-comer who'd be heading south for greater things once he'd cut his teeth in the sticks.