As I understand it, rendering fat is a culinary term for melting and clarifying hard animal fat in dry heat or wet heat for cooking purposes. One application of rendering I have seen is heating animal fat (such as lard or tallow) over low heat for an extended period of time, until the solid fat separates from impurities like proteins, sinew, and connective tissue. The clear liquid that results is called rendered fat, which can be used for other things like sauteing vegetables. However, I also read that rendering can make meat juicier because it allows the melted fat to penetrate the meat fibers, creating pockets of liquid that add moisture and tenderness to the meat as it cooks. Fat is an important component of meat and helps to keep it moist and juicy, so by allowing the fat to permeate the meat fibers, rendering can improve the overall juiciness and flavor of the meat. Can someone confirm if this is indeed how rendering works? If not, if you could explain how rendering improves the flavor of meat? Thanks and any help would be great! 
Speaking as someone who has made this broth, it will not work.  Fresh anchovies will add too much oil and will break up in the broth, making it cloudy and too fishy.  You really want to look at other dried ingredients. The answers to this question cover a fair range of what those dried ingredients could be. 