smart casual
adjective UK uk/ˌsmɑːt ˈkæʒ.ju.əl/ us/ˌsmɑːrt ˈkæʒ.uː.əl/
商务便装式的
(of clothing) neat and stylish, but not too formal, especially when this is the accepted way of dressing for a particular situation, place, or social occasion
The restaurant's dress code is smart casual. 这家餐馆的着装要求是商务便装。