Wagner piece? Tiresome, vacuous work (7)
I believe the answer is:
operate
'work' is the definition.
(I know that work can be written as operate)
'wagner piece? tiresome vacuous' is the wordplay.
'wagner piece?' becomes 'opera' (Richard Wagner wrote operas).
'vacuous' suggests removing the centre.
'tiresome' with its middle taken out is 'te'.
'opera'+'te'='OPERATE'
(Other definitions for operate that I've seen before include "Eat rope (anag.)" , "Perform surgery or run a machine" , "Act, like a surgeon" , "Function; run" , "Make function" .)