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' indicates the answer is hidden within 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?)" .)