Lifeless piece of theatre nicely turned around (5)
I believe the answer is:
inert
'lifeless' is the definition.
(I've seen this before)
'piece of theatre nicely turned around' is the wordplay.
'piece of' indicates a hidden word.
'turned around' says the letters should be written in reverse.
'treni' can be found hidden inside 'theatre nicely'.
'treni' written backwards gives 'INERT'.
(Other definitions for inert that I've seen before include "Disinclined to act" , "like neon" , "Dormant, lifeless" , "Chemically inactive" , "Sluggish, inactive" .)