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' acts as a 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" .)