This is more like an informal explanation of what the term <em>democracy</em> means. It mostly contains short and simple words, so it cannot be a formal definition or a dictionary definition. An extended definition is usually one or more paragraphs, so this text is too short to be an extended definition.
An extended definition is an explanation or illustration of a concept that goes beyond the definition that is normally found in a dictionary. An extended definition provides additional information to the reader in the form of examples or descriptions. In this case, the author tells us that a democracy is not run based on the ideas of a single leader. This description goes beyond the formal definition of democracy and makes this an extended definition.
