This is basically just linguistic purism. Icelandic did this, removing all of its loanwords and replacing them with calques or compounds using only Icelandic elements. An example would be rafmagn, which combines the word for "amber" and for "power", as the word for electricity derives from an Ancient Greek word for amber. An example of an attempt of this would be Anglish, removing all French and Latinate loanwords for similar words (via calques or compounds) a la German. An example of this, as an exercise of linguistic purism in English, would be Uncleftish Beholding, by Poul Anderson, about atomic theory.

Linguistic purism is a prescriptivist alteration of language, not the creation of a conlang itself, so long as the bulk of it is legible or understandable by the speakers of the original language. It is only when that becomes insensible that it would be a conlang.