It is hard to tell from your picture. There are many reds. Usually nurseries have limited number of varieties. You might figure out by knowing what other red clematises they sell. From distant view I would suggest Kardinal Wyszynski. Two other options are Red Cardinal and Westplatte. These are the most popular in nurseries. There are others newer hybrids that look like yours. Sometimes the difference between flowers is just the color of antlers, or shape of sepals. What is also important is plants height, pruning group, flower power. Take another pic with good view of the middle of the flower. It will give more information
