Have produced clematis from seed but find air layering to be most successful method as you over-winter the cutting still attached to the host. I lost too many seedlings the other way. I would do this only to have the excitement of maybe finding a new cultivar.

Am absolute amateur but it goes thus:

After last frost take trailing stem and make a nick in it which you dip in rooting hormone, apparently this has anti bacterial qualities as well. I find a way of elevating a pot containing sterile soil and weight down the nicked stem into this. Leave it in this position until the next spring when you can separate it from the mother plant.

good luck with your seed