Pat and Henry organised female event (3,5)
I believe the answer is:
hen party
'female event' is the definition.
Although both the answer and definition are singular nouns, I don't see how one could define the other.
'pat and henry organised' is the wordplay.
'and' means one lot of letters go next to another.
'organised' indicates an anagram.
'pat'+'henry'='pathenry'
'pathenry' is an anagram of 'HEN-PARTY'.
Can you help me to learn more?
(Other definitions for hen party that I've seen before include "Females celebrating" , "Event to which stags are not invited" , "occasion lacking men" , "Female-only gathering" , "Women's gathering (colloq.)" .)