11Ac Conductors in Boston have nothing to go on after this (4,5) L?S? T?A?N. It looks as if it has to be LAST TRAIN, but why? Clue of the Week :- McEnroe, say, magnificent on grass (9) S???????? (originally in The Independent, Eccles)
I'm sorry, I don't understand your "a distraction". Please explain. Having checked Chambers, I see that one of the meanings given is "a railway guard (N Am)". So I suspect the N Am is the justification for Boston. Do you agree?
Yes, it's an indication that a conductor is a train guard specifically in the US, and Boston is a misdirection to make you think of the famous Boston Symphony Orchestra.