My DSD lives with us and turns 18 next month. She has a Saturday job, and also worked a lot of days during the summer hols. My DH gives her an allowance for clothing, not a set amount each month, but only yesterday she asked if she could give him her "expenses" and to be honest, I do not know how much she receives or expects each month. I asked DH why he was doing this, and he said that he will provide her with essential clothing such as underwear, or yesterday, as it turned out, jumpers. She said that on the same receipt, there was a dress, but this was a "treat" she would pay for, but insisted that jumpers and leggings are essential items.
At that age I advised him, I would save for items with my earnings, or ask for them as birthday or Xmas presents (topical at present!).
Any advice appreciated as she has lived with us for less than a year so I am a relatively new SM who feels she has no control over the situation!