Perform a double act with a bird (4)
I believe the answer is:
dodo
'bird' is the definition.
(dodo is a kind of bird)
'perform a double act' is the wordplay.
'perform' becomes 'do' (both can mean complete an action).
'a double act' becomes 'do' (to do is to act or execute a task. I am not sure about the 'double' bit.).
'do'+'do'='DODO'
'with a' acts as a link.
Can you help me to learn more?
(Other definitions for dodo that I've seen before include "Proverbially extinct bird" , "bird long dead" , "Idiot" , "Bird (whose style of very out of fashion)" , "Old bird" .)