On a golf course, the fairway is the long strip of short, neat grass between where you start (the tee) and where the hole sits (the green). You are supposed to hit the ball along it. If you miss, the ball sits in the rough — longer grass, harder to play. Golfers say a shot is “in the fairway” when it landed where they hoped. In ordinary talk now, this is almost only a golf word. Ships once used fairway for a clear path through water, but that is not the sense you are learning here. Though actually, the fair in fairway is the old sense “open, clear, good to travel,” not “treating people justly.” A fairway is not a road, and you do not walk it the way you walk a path: you send a ball along it. The well-kept middle is the point; the word is praising how clear that strip is, compared with the messy grass on either side.