Word: opus
A work of music or set of works with a specified rank in an ordering of a composer's complete published works. Example: Beethoven's opus eighteen quartets are considered by many to be the beginning of the Romantic era.
A work, especially of art. Example: The painter's last opus was a dedication to all things living, in a surprising contrast to all of his prior work.
You can find a list of possible crossword clues for OPUS below.