The Verification Problem in abstract argumentation consists in checking whether a set is acceptable under a given semantics in a given argumentation graph. Explaining why the answer is so is the challenge tackled by our work. In this extended abstract, we focus on a small part of this aim considering only the defence principle and proposing explanations in order to explain why a subset of arguments defends all its elements. These explanations are visual, in the sense that they take the form of subgraphs of the initial argumentation framework. They form a class, whose properties are investigated.