Allusion
Allusion: a reference to something in literature, history, mythology, religious texts, etc., considered common knowledge.
The verb form of the noun “allusion” is “allude, “so you could state that a writer “alludes to” or “makes an allusion to” something. For instance, “Chocolate cake is my Achilles heel.” The allusion here is to “Achilles’ heel,” or the Greek myth about the hero Achilles and how his heel was his one weakness. In this case, the speaker’s “weakness” is chocolate cake.