Double act now extinct (4)
I believe the answer is:
dodo
'now extinct' is the definition.
I know that 'extinct' relates to this 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' duplicated is 'DODO'.
Can you help me to learn more?
(Other definitions for dodo that I've seen before include "Proverbially dead bird" , "Native of Mauritius" , "Idiot" , "one very dead!" , "Proverbially extinct bird" .)