There are two ways to solve the problem. The first, as described by Bob, would be to open your stance to the extent needed to avoid the string hitting your clothes.
The second is less obvious, which is to close your stance even more, so that the string touches the left side of your chest (for a RH shooter) at full draw, but does not brush against your clothes when you shoot the bow. Women are familiar with this method, for reasons I probably don't need to explain, but it works for men too.