Statement of aims about encore (5)
I believe the answer is:
credo
'statement of aims' is the definition.
(I've seen this before)
'about encore' is the wordplay.
'about' becomes 'c' (abbreviation for circa).
'encore' becomes 'redo' (I've seen this in another clue).
'c'+'redo'='CREDO'
(Other definitions for credo that I've seen before include "Section of mass" , "Doctrine or belief" , "music in church" , "Part of the Latin Mass" , "mission statement" .)