Boolbar - you are correct on this one. But the reason I dislike it is because (a) it's ambiguous - the answer could just as easily be bookend; (b) there's no definition, purely a device; and (c) even as a device it's flawed because it's not indicated (e.g. with the phrase "to a setter"). These "inverse clues" are becoming more prevalent, but I don't think they're big or clever.
[Raak] That is true. You can make up several answers that match some of these clues - like O (4,6) = Come second. My 'v' is much the same, but is a famous schoolboy joke.
[Bb] Centre of Gravity, ha ha. No, mine isn't the start, end or middle of anything. Or the second. Or even "a letter in the word 'open'". [Blob] I said not when I said "No-one's got mine yet".