A person who has recently or suddenly risen to a higher social or economic status but has not yet gained the acceptance or recognition of others in that class.

Despite his wealth, the parvenu struggled to fit in with the established elite at the gala.

parvenuadjective

Relating to someone who has recently acquired wealth or social status but is not yet accepted by the established elite.

The parvenu businessman flaunted his new wealth with extravagant parties, hoping to gain acceptance among the city's elite.