Act after act succeeded ... they're all dead now (5)
I believe the answer is:
dodos
'all dead now' is the definition.
Although both the answer and 'now' are nouns, they are not in the same form of the noun.
'act after act succeeded' is the wordplay.
'act' becomes 'do' (to do is to act or execute a task).
'after act' becomes 'do' (to do is to act or execute a task. I am not sure about the 'after' bit.).
'succeeded' becomes 's' (genealogical abbreviation).
'do'+'do'+'s'='DODOS'
'they're' is the link.
Can you help me to learn more?
(Other definitions for dodos that I've seen before include "Extinct flightless birds" , "They never got up" , "they're no more" , "Extinct birds of Mauritius" .)