Hi In this context, to sweat is to work hard; a den is a place where people live or work - the word den can be used quite negatively So, a sweater's den is where people work hard in unpleasant circumstances. It's a good phrase but, nowadays, we would probably say that it is a sweatshop In your sentence, the people are doing good work - making clothing, I would guess - but they are having to live and work in a terrible place Dave
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