Girl is touring Rhode Island (4)
I believe the answer is:
iris
'girl' is the definition.
'is touring rhode island' is the wordplay.
'touring' means one lot of letters goes inside another (touring can mean going round).
'rhode island' becomes 'ri' (US postal abbreviation).
'is' placed around 'ri' is 'IRIS'.
(Other definitions for iris that I've seen before include "Film about writer _______ Murdoch" , "Goddess of the rainbow in the eye" , "Flower - girl's name" , "who keeps pupil in?" , "Nice flower or eye part" .)