Yes it can be done exposing only one side of the wall. The standard method for correcting this problem is to saw into the 2×4 on the inside bellow. Do not saw all the way through. You do not want to cut the 2×4 into two pieces. After sawing about two-thirds of the way through, hammer in a wood wedge. This will actually lengthen the one side of the stud and straighten it out. Once it is straight, screw straps to both sides of the stud to restore its rigidity and strength.