Female-only gathering (3,5)
I believe the answer is:
hen party
'female-only gathering' is the definition.
(I've seen this before)
This is all the clue.
(Other definitions for hen party that I've seen before include "One last night of debauchery" , "A social gathering confined to women" , "Females celebrating" , "occasion lacking men" , "Event to which stags are not invited" .)