All set for the day theatre's absurd (2,3,5)
I believe the answer is:
at the ready
'all set for' is the definition.
I know nothing about this answer so I can't tell whether it can be defined by this definition.
'day theatre's absurd' is the wordplay.
'absurd' is an anagram indicator.
'day'+'theatre'='daytheatre'
'daytheatre' anagrammed gives 'AT THE READY'.
'the' is the link.
Can you help me to learn more?
(Other definitions for at the ready that I've seen before include "Available for use in operating" , "Prepared or available for immediate use" , "on standby" , "Prepared for instant action" , "Poised for action" .)