Ready to alter afresh (5)
I believe the answer is:
alert
'ready' is the definition.
(I've seen this in another clue)
'alter afresh' is the wordplay.
'afresh' indicates an anagram.
'alter' anagrammed gives 'ALERT'.
'to' acts as a link.
(Other definitions for alert that I've seen before include "'Attentive, vigilant (5)'" , "sharp-witted" , "Danger warning" , "Signal danger" , "Wide-awake and watchful" .)