Not all those twits will be ready (3)
I believe the answer is:
set
'be ready' is the definition.
('set' can be similar in meaning to 'ready')
'not all those twits will' is the wordplay.
'not all' indicates the answer is hidden within the clue.
'SET' can be found hidden inside 'those twits will'.
(Other definitions for set that I've seen before include "carriage" , "Customary < scenery < a TV < series" , "Put down the tennis group" , "Series of tennis games" , "Major division of tennis match" .)