Mature women to leave party (5)

I believe the answer is:

group

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

'leave party' is the definition.
(I know that party is a type of social affair)

I cannot understand how the rest of the clue works.

Can you help me to learn more?

(Other definitions for group that I've seen before include "A number of elements with something in common (50" , "Take That, perhaps" , "Aggregation" , "Band, assembly" , "Unit of pop performers" .)

I've seen this clue in The Telegraph.

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