Crossword Genius

A group of under 40 people? (6-9)

Ross

I believe the answer is:

thirty-something

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

This might be a double definition.

'a group' is the first definition.
Although both the answer and definition are singular nouns, I don't understand how one could define the other.

'of under 40 people?' is the second definition.
The definition suggests a singular noun which matches the answer.

Can you help me to learn more?

I've seen this clue in The Sunday Times and The Times.
Want a hint initially instead of a full solution? Install my app