I would say, if possible find a spot where it gets a few hours of sun in the morning but is in shade be the afternoon and evening. Dig a large hole, get rid of the clay soil from the hole, and fill the hole with the most moisture retentive soil you can find, then add a layer of mulch. Clay drains slowly so it should have a sort of bathtub effect. When you water, water deeply flooding the plant and saturating the new soil in the hole. The mulch should help the water from evaporating and the clay will slow the draining away.
