Michelangelo's only signed work
I believe the answer is:
pieta
'michelangelo's only signed work' is the definition.
(I've seen this in another clue)
This is all the clue.
(Other definitions for pieta that I've seen before include "Statue of Mary with body of Jesus" , "Image of Mary with the body of Christ" , "Religious figures" , "Status of Virgin with body of Christ" , "Post-Crucifixion scene sculpture" .)