Clarendon, Arkansas is the seat of Monroe County and is located in the southeast quadrant of the Natural State. It also sits at the mouth of the Cache River, for which the Cache River National Wildlife Refuge is named. The refuge made headlines on April 28, 2005, when a team of scientists led by the Cornell Laboratory of Ornithology announced sightings of the ivory-billed woodpecker, long thought to be extinct. Of course, this claim has been challenged by other researchers, and the debate continues today.
Clarenden is listed as a high-probability typo. There are 27 entries in OhioLINK, mostly in connection with Clarendon Press. It will take a bit of effort resolve these errors in your own catalog, as they’re likely to occur in transcribed fields.
(Campephilus principalis, published in Jacob Henry Studer's The Birds of North America, from Wikimedia Commons)