If you are looking for the crossword puzzle answer, a brash young woman could also be called a ladette.
ladette
A "Flapper"
The word impertinent can mean rude, brash, or lacking respect. So, the phrase 'impertinent young girl' may mean a girl that is either brash or rude.
She was a brash young woman, and it got her noticed by management. The staid board of the exclusive club resented the appearance of this brash new member. The marketing team hit upon a novel idea, and they rode this brash new concept all the way to the bank. As we look at its definition, brash is bold, but edgy or even offensive. It's lacking in tact or a sense of shame. But you probably knew that. Good for you.
A brash young girl is typically a bold and assertive young female who is often outspoken and impulsive in her actions and words. She may not be afraid to speak her mind or take risks, often displaying confidence and a strong sense of independence.
Peter Brash was born in 1954.
Alan Brash was born in 1913.
Brash Brands was created in 2006.
Brash Entertainment was created in 2007.
Brash Entertainment ended in 2008.
Thomas Brash was born in 1874.
Thomas Brash died in 1957.