M.C. Beaton: Agatha Raisin and the Haunted House [2006] paperback

Reports of a haunted house soon have Agatha snooping around, but it turns out the victim is a universally disliked old biddy and someone is playing a practical joke. And then the old lady is murdered - but for Agatha, solving a crime is much more fun than hunting a ghost! Very soon she's up to her usual tricks, involving the villagers, local police, and, of course, her handsome new neighbour...