Operatic lead is getting on with performance finally (6)
I believe the answer is:
isolde
'operatic lead' is the definition.
The definition suggests a singular noun which matches the answer.
'is getting on with performance finally' is the wordplay.
'getting on' becomes 'old' ('getting on a bit' means 'old').
'with' means one lot of letters go next to another.
'finally' says to take the final letters.
The final letter of 'performance' is 'e'.
'is'+'old'+'e'='ISOLDE'
Can you help me to learn more?
(Other definitions for isolde that I've seen before include "Tristram's lover, quite soiled" , "Soiled like Tristan's lover" , "Lover of Tristan" , "for Tristram" , "Tristan's mate" .)