Complex sentence: Only women of ill-repute or low social standing allowed themselves to be seen not wearing a corset, so wearing a corset was a way to communicate that you were an worthy female member of polite society.
Split into simpler sentences: Only women of ill-repute or low social standing allowed themselves to be seen not wearing a corset. Wearing a corset became a way for a woman to communicate that she was a worthy female member of polite society.