Girl finished before county (7)
I believe the answer is:
donegal
'county' is the definition.
(county of Ireland)
'girl finished before' is the wordplay.
'girl' becomes 'gal'.
'finished' becomes 'done' (both can mean completed).
'before' means one lot of letters go next to another.
'gal' after 'done' is 'DONEGAL'.
(Other definitions for donegal that I've seen before include "part of Ireland" , "Lean dog (anag) - Irish county" , "County of NW Ireland" , "County of NW?Ireland" , "Ireland's northmost county" .)