Music from Octopussy (4)
I believe the answer is:
opus
'music' is the definition.
(opus is a kind of music)
'from octopussy' is the wordplay.
'from' says the answer is hidden in the clue.
'OPUS' is hidden within 'octopussy'.
(Other definitions for opus that I've seen before include "Soup (anag.)" , "Work of 25 perhaps" , "Work (mus.)" , "Creative work, eg in writing, art or music" , "Work (of a composer?)" .)