You could take it to a dry cleaners, who would fix it up quite easily I imagine. OR, if you have one, you could use a steamer. Failing that, using a damp towel and an iron on it’s lowest setting will do the job. Just put the towel over the crease and iron over the top of that. The steam that appears will help more than the direct heat. Always test an unseen spot first though to be on the safe side and check every few touches to make sure all is well. :)