The most common and most likely answer to this crossword clue is the 7 letter word DONEGAL
I've seen this crossword clue in The Guardian
D
O
N
E
G
A
L
More clues leading to the result DONEGAL
- Irish county tricked colleen
- Party girl with quarters in the Lifford area
- Irish county visited by girl
- Accomplished objective, taking over county
- Spread of Gaeldom after finally advancing here?
- County female finished on top
- Vagrant longed to tour a county of Ireland
- County girl supporting academic type with energy
- Irish county finished with colleen
- Completed festivity almost in part of Ireland
Buddy explains!

The straight part
We know that "County" is the straight/definition part of the clue. The straight part is often a synonym or definition, in this case county = donegal.The cryptic/wordplay part
In cryptic crossword there's often an wordplay/cryptic part as well.This part involves a more complex hint, such as an anagram, homophone, hidden word, etc.
Sadly, We don't have an explanation for this specific crossword clue yet.