Relatively young ladies (6)

I believe the answer is:

nieces

I'm a little stuck... Click here to teach me about this clue!

Here is my best explanation:

'relatively young ladies' is the definition.
The answer and definition can be both people as well as being plural nouns.
Maybe they are linked in a way I don't understand?

This is all the clue.

Can you help me to learn more?

This clue was last seen in Evening Standard