Teds + Brio + (Bridge of) Allan = Llanbister Road
Although it really needs another "R".
You're mentally pretty much on the right track (and exercising great ingenuity); but none of your references are right; and, the clue doesn't involve an anagram.
If this helps any: "my third" (as the riddlers say) is a three-letter word: which -- all on the far side of Inverness -- makes part of the name of a railway station; and also part of the name of a geographical feature about fifty miles north-east of that station.