Hopefully your clematis isn't dead!!..Living in your cold zone..aren't potted plants left out to the winter elements not a good thing?..I always understood they have no insulation and are subject to winter kill..In saying this go ahead and hard prune it ...start from the ground and find the 3rd leaf axil and prune above that..then give it some fertilizer..either 13-13-13 or rose fertilizer and keep the soil moist..not soggy but moist..Hope you see some green leaf buds form afterwards..it's still early yet in your zone..so here's wishing you the best of luck!!..You might consider wrapping the pot/putting in a sheltered area or bringing into the garage next winter...Let us know!!..Jeanne

It may not be dead. Some of my type 3's are barely coming up from the ground while my type 1's are blooming and 2's are budded.

Several of my type 3's did not sprout from the old vines but up from the ground only.

Earnest is rated down to zone 4