Girl on an excursion? (5)
I believe the answer is:
sally
This clue is a double definition.
'girl' is the first definition.
(feminine given name)
'an excursion?' is the second definition.
(I've seen this before)
'on' is the link.
(Other definitions for sally that I've seen before include "- - Lunn, flat cake" , "Witty comment" , "Sortie - Gracie Fields song" , "Sortie; quip" , "Sarah might make a witty remark about the willow" .)