This was not an easy one, for some reason. I saw lots of things that were on their own, this week, but nothing that suggested 'single'. So I did what I usually do and went to the dictionary, in hope of inspiration through definition, and I found this: Single 3. consisting of one part. (of a flower) having only one whorl of petals.
So you get another flower picture from me this week - a pinky white Potentilla