Writer shuns a universal god (4)

I haven't cracked this one yet — but the brilliant team at Times for the Times have:

{au} THOR (writer) [shuns a universal]. I had this originally as THOR{au} and suspected an error in  the clue as the famous American writer is spelt ‘Thoreau’ but there’s nothing to indicate deletion of the ‘e’. Anyway it turns out that the error was my own since the wordplay is much more simple than I was trying to make it. Many thanks to Kevin Gregg for pointing this out and to Bletchley Reject for considering the same route to the answer as mine, although he was wise enough to reject it and think again. [Edited at 05:50 BST]