Can't get 11 across...

Good news is that if you want to keep your brain ticking over as you get older, the best way it seems is by doing mental exercises like crosswords and sudoku.  Good news (for me) because I do these pretty well every day.  Not, you understand, that I always complete them - but as I understand it, that's not the point.  To paraphrase the Olympic ideal, it's not the succeeding but the taking part that matters.  What I am finding as I get older is that I suffer from "brain freeze" more often than I used to - that's when you know you know a word, or the answer to something but just can't bring it to mind.  A sort of extreme example of "it's on the tip of my tongue".  On a quiz programme the other day was a list of books and the question was - who wrote them.  And I'd read them - all of them - and I knew the authors.  But could I bring a single name to mind??  Frustrating isn't the word!