Girl in an Irish county (5)
I believe the answer is:
clare
I believe this clue is a double definition.
'girl' is the first definition.
'an irish county' is the second definition.
(County Clare in Ireland)
'in' is the link.
(Other definitions for clare that I've seen before include "She's a country girl" , "sister" , "The Banner county" , "John --, English poet; Irish county" .)