alignment wont resolve that you have uneven wear on the tire. it will fix your alignment but if you dont get a new tire you will still have tire wear present. and then 6 months down the road you will take your car back saying...i had an alignment...why is there wear here?
so...buy two new tires and get an alignment while rotoating front tires to rear...since the other side is worn probaly as well.

likely cause of tire wear is.......drum roll please....
lack of rotation...rotate your tires every 5,000 or so.
camber
hard driving....example..ebrake drifter?

if both rear tires have been on vehicle for same amount of time...then you can rule out toe. if toe was out of spec then both rears would show the same wear...meaning your vehicle dogtracks down the road.
camber is non adjustable in the rear...or front for that mastter....so your best bet is to rotate your tires more often.