Complex sentence: The West Highland Line connects Fort William and Mallaig, and was a crucial vein for the local fishing industry and the highlands economy in general, which suffered enormously after the Highland Clearances of the 1800s.
Split into simpler sentences: The West Highland Line connects Fort William and Mallaig. It was a crucial vein for the local fishing industry and the highlands economy in general which suffered enormously after the Highland Clearances of the 1800s.