Priest’s backing change and still preaching about it (10)
I believe the answer is:
altarpiece
'priest's backing' is the definition.
The definition and answer can be both man-made objects as well as being singular nouns.
Perhaps there's an association between them I don't understand?
I cannot understand how the remainder of the clue works.
Can you help me to learn more?
(Other definitions for altarpiece that I've seen before include "Painting placed prominently in church" , "Religious work" , "communion table artwork?" , "Work of art in church" , "Church artwork" .)