The Cunning Man by Robertson Davies.
Dr. Jonathan Hullah is a practitioner of holistic medicine in Toronto and a renowned diagnostician (the "cunning man" of the title, in fact). As the novel opens he's being interviewed by his late godson's widow Esme (who also happens to be a journalist) about some matters relating to the death of the local vicar; Hullah is reluctant to be drawn on the details (for reasons that become clear much later) and instead launches into a series of reminiscences taking us back to his childhood in Sioux Lookout and his later life in Toronto, including the setting-up of his medical practice and the array of intriguing and amusing characters presenting themselves for treatment.
Many of the anecdotes revolve around the local church, St. Aidan's (apparently a thinly fictionalised version of a real Toronto church), its clergy (including Hullah's old friend Charlie) and those who live nearby, including Hullah's landladies, a couple of genteel artistic lesbians. Hullah himself is involved for much of the book in an affair with Nuala, the wife of another old friend, Brocky, and the mother of Connor (husband of Esme) who is murdered in circumstances never fully explained.
Like a lot of books structured in this way (including a couple of previous entries in this series of posts) a lot of diverting anecdotal reminiscence doesn't add up to much in the way of what you'd call a plot, but that doesn't really matter when it's as entertainingly written as this. Davies' writing wears its erudition pretty lightly, but there are all manner of throwaway literary and cultural anecdotes, much entertaining sparring between Hullah and Charlie about the conflict between science and religion, and a few deaths at the end just to tie up a few loose plot strands.
[Just to pick up on one of the literary anecdotes as an example: it's true that W.B. Yeats had an operation late in life to try and restore his sexual vigour - but while it's referred to as "the Voronoff operation" in the book (which would imply some sort of monkey gland graft) most information I could find suggests it was the more mundane Steinach operation, i.e. a vasectomy.]
Incidentally this is the second book in this series to feature the city of Toronto as a major character - Michael Ondaatje's In The Skin Of A Lion being the other.