Being leather-lined, you should be able to use a stretching spray without any problem. Spray the inside of the shoes (not the outside) where it feels tight, and then put your feet straight into them so that the shoe softens up where the pressure is against your foot. Walk around in them for a while to give the leather a chance to stretch.
I've used this one before on several pairs of my shoes that were a bit tight when they were new, and it's worked really well. You can get it from those cobbler/key cut places inside major shopping centres, and a few shoe shops also stock it. It cost around $8 when I got it.http://www.waproo.com.au/product.php?Pr ... at=7&No=15