Différance functions in all language. The word différance means to differ and to defer. Derrida's theory is that all meaning is always already deferred. Therefore, no meaning is ever fully present. To make a simple example, take any word and define it. The word 'elephant' is an animal that is large (relative to most other animals); the elephant lives in the wild. The word 'elephant,' by itself, means the concept 'elephant.' But to know what the word and/or concept means, we need to know all of these other things similar and different to the elephant: "animal," "wild," "large." Therefore, the meaning of elephant (or anything) is never fully present because it defers to all of these different things.
One of the philosophical applications of différance and this deferring difference is the deconstruction of binary oppositions. Derrida notes binary oppositions in which the first (primary) term is privileged over the secondary term and this privilege often has to do with presence. For example, in speech/writing, speech has historically been considered more present (closer to the speaker's mind and internal thought). But Derrida shows how writing is a supplement to speech. More significantly, with différance, he shows how the written word has more present meaning than the spoken word. (Différance and difference in French sound the same; they need to be written to see the difference between the two. Therefore, the meaning, indicated by that difference can only be seen in written form; not in speech.)
There are endless applications of this kind of deconstruction, thematically speaking. The deconstruction/decentering of things like anthropocentrism or geocentrism are obvious. That is, these shifts in thought structures are analogous to the shifts of meaning via différance (like the elephant) and the shifts in relationships between binary oppositions.
Waiting for Godot would be an interesting text to study with différance in mind. The play raises more questions than it answers. Therefore, the meaning of the play and its particulars necessarily shifts, moves, and decenters with each reading, whether that is by a critic or the average reader.
In his essay, "Différance," Derrida clarifies what différance is and what it is not:
It is not a present being, however excellent, unique, principal, or transcendent. It governs nothing, reigns over nothing, and nowhere exercises any authority. Not only is there no kingdom of différance, but différance instigates the subversion of every kingdom.
Although différance is a single word, we don't have to look for a single word to find examples. Look for examples where a thought structure is subverted or toyed with. Différance is the shift in meaning; in the context of deconstruction, it is the shift in structural meaning.
In The Great Gatsby, Gatsby's ideal vision of Daisy is always elusive, being a product of the past and of his imagination; it is, in this sense, always already deferred (a romantic différance).
In "Anecdote of the Jar," Stevens writes that the jar placed on a hill tamed the wild. "The wilderness rose up to it, / And sprawled around, no longer wild." The 'presence' of the jar structured the landscape. But Derrida would reply that this presence (center) is subject to différance and deconstruction. This center limits the freedom of the natural world and diversity of meaning. Allegorically, the "dominion" of the jar's presence could, and maybe should, be rebelled against.