Its double act did not survive (4)
I believe the answer is:
dodo
'act did not survive' is the definition.
I can't judge whether this defines the answer.
'its double' is the wordplay.
'its' becomes 'do' (I am not sure about this - if you are sure you should believe this answer much more).
'double' indicates the doubling of some letters.
'do' duplicated is 'DODO'.
Can you help me to learn more?
(Other definitions for dodo that I've seen before include "Native of Mauritius" , "Ultra-conservative" , "bird long dead" , "Repetitive extinct animal" , "Two rooks - one was unable to fly" .)