1: Having a sharp and rather sour taste.
2: Sharp or bitter in tone or meaning.
3: A pastry case, especially one without a top, with a sweet or savoury filling.
4: A promiscuous woman. The often unisexual nature of modern slang ensures that the meaning of 'tart' in this context can also be applied to promiscuous males. There are variations to this, such as 'tarted up', which basically means getting dressed up in a potentially garish way. Y'all might call, tarted up, 'dolled up'.
This posting is in reference to definition number 3.
The above photograph is of a Bakewell Tart. Bakewell is a town in Derbyshire, set right in the heart of the Peak District National Park. Here's some information on Bakewell : Bakewell, Derbyshire. Here's one recipe for a Bakewell Tart : Bakewell Tarts. Just to confuse you, you will note there are many different ways to make a Bakewell Tart.
Bakewell is about twenty five miles north east of where I live. Yes, I really do live in a town named Leek. I'm thinking of driving to Bakewell in search of a classic Bakewell Tart. Oh and I am referring to the pastry item.