Alert for a change in the future (5)
I believe the answer is:
later
'in the future' is the definition.
(I've seen this in another clue)
'alert for a change' is the wordplay.
'for a change' indicates an anagram.
'alert' is an anagram of 'LATER'.
(Other definitions for later that I've seen before include "After a given point in time" , "Tomorrow (or next week)?" , "Eventually" , "Afterward, subsequent" , "At some time afterwards" .)