Musical drama, the heartless work (7)
I believe the answer is:
operate
'work' is the definition.
('operate' can be a synonym of 'work')
'musical drama the heartless' is the wordplay.
'musical drama' becomes 'opera' (I've seen this before).
'heartless' suggests removing the centre.
'the' with its centre removed is 'te'.
'opera'+'te'='OPERATE'
(Other definitions for operate that I've seen before include "Manage, run" , "Perform as surgeon does" , "Make to work" , "Cut - run" , "Carry out surgery" .)