Carry out again (4)
I believe the answer is:
'carry out again' is the definition.
('do' can be a synonym for 'carry out' so perhaps 'redo' is OK for 'carry out again')
This is all the clue.
(Other definitions for redo that I've seen before include "Decorate (eg a room) again" , "Redecorate or repeat action" , "Make anew" , "Fashion again" , "Have second thoughts" .)