"Goodnight" girl (5)
I believe the answer is:
irene
'goodnight girl' is the definition.
(I've seen this in another clue)
This is all the clue.
(Other definitions for irene that I've seen before include "Female name" , "Girl of peace" , "Representative of peace" , "One can find a girl in Ree" , "Girl's name; Soames Forsyte's first wife" .)