The most common and most likely answer to this crossword clue is the 5 letter word WENCH
I've seen this crossword clue in The Sunday Telegraph
W
E
N
C
H
Buddy explains!

The straight part
We know that "Young woman" is the straight/definition part of the clue. The straight part is often a synonym or definition, in this case young woman = wench.The cryptic/wordplay part
In cryptic crossword there's often an wordplay/cryptic part as well.This part involves a more complex hint, such as an anagram, homophone, hidden word, etc.
Sadly, We don't have an explanation for this specific crossword clue yet.
What does WENCH mean?
WENCH noun- (possibly offensive) A girl or young woman, especially a buxom or lively one.
- Used as a term of endearment for a female person, especially a wife, daughter, or girlfriend: darling, sweetheart.
- A woman servant; a maidservant.
- A promiscuous woman; a mistress.
- A prostitute.
- A black woman (of any age), especially if in a condition of servitude.
- To frequent prostitutes; to whore; also, to womanize.