I have had a large conifer (30ft) cut down and the holly tree next to it is more or less bare down one side due to the conifer. Could the holly adapt now it will have light and grow properly?
Yes, I would say that your holly will in time, fill in the space that was previously shaded by the now felled conifer. Late summer is a good time to prune or trim holly and this may also stimulate growth to sprout on the bare side.