Double act no longer with us (4)
I believe the answer is:
dodo
'no longer with us' is the definition.
I can't judge whether this definition defines the answer.
'double act' is the wordplay.
'double' shows that letters should be duplicated.
'act' becomes 'do' (to do is to act or execute a task).
'do' doubled is 'DODO'.
Can you help me to learn more?
(Other definitions for dodo that I've seen before include "Idiot" , "Ultra-conservative" , "Repetitive extinct animal" , "One deeply reactionary" , "Proverbially dead bird" .)