Remove from opera set (5)
I believe the answer is:
'remove' is the definition.
(to erase is to remove)
'from opera set' is the wordplay.
'from' indicates a hidden word.
'ERASE' is hidden within 'opera set'.
(Other definitions for erase that I've seen before include "Efface" , "Delete" , "Do away with" , "Scratch" , "Obliterate" .)