Seeking an evergreen shrub for a plant bed

I have a plant bed that has lavender (Imperial Gem, and more recently infilled with Munstead). However a few of the lavender plants have died off. The bed is locate on the east side of the house and runs north to south alongside a driveway, and gets a good amount of sun each day. It's approximately 10-15 metres from an oak tree. The soil is compacted clay though I did dig in bags of compost when I planted the original lavender. As it is at the front of the house and on show, I'd like to infill it with an evergreen shrub (dwarf), keeping what lavender has survived. Any recommendations?