Clustering can be a first step in understanding complex interactions interactions among financial variables. As a simple example we can cluster assets (whose return time series represent its distribution) to understand how assets are related to each other.
Useful Links - https://arxiv.org/pdf/1506.00976v2.pdf, https://www.datagrapple.com/Tech/GNPR-tutorial-How-to-cluster-random-walks.html, http://eliassi.org/papers/henderson-sac15.pdf