Sister asking to borrow my coat

My sister is in her early 20s, doesn’t work, doesn’t want to work & spends all her money on cosmetic treatments. I have this nice coat I wear every so often & she sent me a message asking to borrow it for a date because her coat doesn’t go with her outfit. Thing is she never comes to see me, is known for getting up late in the afternoon and she’s promised to bring it back the following morning at 10am How do I politely say no because I know she’s hoping she can keep hold of it and hope I forget about it, I’ve known her all her life and I know because she’s broke she will try to keep it, she even asks for me to give her money and I’ve given her things in the past and when she does come over she just asks for food. She didn’t even get her niece (my daughter) anything for Christmas.