The answer is no and I’ll explain why. The classification of the species is decided by experts and it is still not fully settled. Early on, up to 200 years ago, scientists got the classifications wrong or a least it has been adjusted and improved. Perhaps at one time they thought that clouded leopards were leopards but not today. Thanks to DNA analysis the science of taxonomy it is more accurate nowadays.
In fact my research tells me that based on morphological characteristics (how they are made) and how they sound the clouded leopard is in the same group as the leopard. However molecular studies tell us that the clouded leopard appeared much earlier than the Panthera cats. It is believed that the clouded leopard diverged about 8.66 million years ago. The Panthera group diverged from other cat species about 11.3 million years ago.
In fact, I think the question is asking if clouded leopards are a subspecies of the common leopard. The answer to that question is No. The clouded leopard is a different species to the leopard. Both the leopard and clouded leopard evolved in the Panthera lineage as shown in the illustration above. As can be seen the clouded leopard was the first to diverge from the ancestral line followed by the snow leopard.
Although the clouded leopard is in the same evolutionary line as the leopard, the genus in which it is classified (Neofelis) is generally placed at the base of the Panthera group but not included in the genus itself.
Conclusion: Are clouded leopards really leopards? No, is the answer.