Large Scottish isle (4)
![Ross](/clue/static/ross-mug.min.png)
I believe the answer is:
skye
(Other definitions for skye that I've seen before include "Home of the Cuillin mountains" , "Largest island of Scotland's Inner Hebrides" , "Where Bonnie Prince Charlie fled after his defeat at Culloden" , "Destination of a princely boat trip" , "part of Scotland" .)