From Longman Dictionary of Contemporary Englishworking clothesworking clothes (also work clothes)DCC clothes which you wear for work or are designed for people to work in → working
Examples from the Corpus
working clothes• As he approached them, Mungo could see that they wore blue uniform trousers under their working clothes.• But she had to turn up at Maggie's school in her working clothes.• They went from the workplace into the canteen, they sat and opened their lunchboxes in their working clothes.• They woke on Sunday morning and people wre going to church ... they daren't be seen in their working clothes.• In fact I felt rather a lout in my working clothes among the elegant gathering.• Jonadab was not to be hurried and methodically finished changing into his working clothes before putting in an appearance.• Still clad in her tattered working clothes, her wellingtons pumped away assiduously to give the instrument the breath it required. 