May not be the easiest clematis to get your hands on but I think Clematis fasciculiflora will fit the bill. Evergreen (great foliage), blooms in winter, fragrant but small nodding cream colored flowers and a reasonably sized vine to boot. Growing in a container is entirely possible, which is not a statement I would make about most very late/very early flowering clematis. Most are species and can get enormous (armandii, montana, cirrhosa, etc.).

A second (and far more distant choice) would be one of the xcartmanii hybrids like 'Avalanche' or 'Early Sensation'. These are also much smaller vines suitable for container growth but I don't find them to be very robust or long-lived. Fussy, in other words :-)

If you aren't firm on the idea of clematis, check out Gelsemium sempervirens Margarita, a vine which blooms quite early with yellow flowers. It's hardy to about -10F.