I've been mending a nightshirt recently and as I was sewing I remembered that I had bought this nightshirt (second hand of course!) originally to wear as a day time shirt. I never wore it much and decided it was better as a nightshirt. It has been a very succesful nightshirt to the extent that it was starting to fall apart. The mending project reminded me of the wisdom of the adage 'a stich in time saves nine'!
I've done this a few times, bought an item and then used it in a different way than I had originally intended. I've got a long sleeved V-necked t-shirt that I now more often wear as a thin jumper over a lacy blouse; a scarf that I use as a belt; a lacy sleeveless vest top that I never wear now by itself but always with a blouse underneath and a cheongsam that I wear over a long sleeved t-shirt and trousers.
Mixing and matching is fun and it makes me feel I have more clothes as well as helping to prevent waste (though as i always donate unwanted clothes to second hand shops then they wouldn't really be wasted!).
Have you given any items of clothing a new lease of life by redefining what they are?