Cleft sentence

a sentence in which a simpler sentence is paraphrased by being divided into two parts, each with its own verb, in order to emphasize certain information, especially a sentence beginning with expletive it and a form of be followed by the information being emphasized, as it was a mushroom that alice ate instead of alice ate a mushroom.
also called pseudo-cleft sentence. a two-part sentence in which a subject or subject complement expresses information being emphasized and an indefinite relative clause corresponds to the rest of a simpler sentence that has been paraphrased, as a mushroom was what alice ate or what alice ate was a mushroom.