Part of opera to cut from Tosca , retaining tenor’s second note (5)
I believe the answer is:
scena
'part of opera' is the definition.
(Italian term for a scene in an opera)
'to cut from tosca retaining tenor's second note' is the wordplay.
'cut from' is a deletion indicator.
'retaining' is an insertion indicator.
'tenor's second' becomes 'e' (2nd letter of 'tenor').
'note' becomes 'n' (abbreviation).
'tosca' with 'to' taken away is 'sca'.
'e'+'n'='en'
'sca' placed around 'en' is 'SCENA'.
(Other definitions for scena that I've seen before include "dramatic musical selection" , "Part of an opera" , "Dramatic vocal solo" .)