Watchful for a later change (5)
I believe the answer is:
alert
'watchful' is the definition.
(similar in meaning)
'a later change' is the wordplay.
'change' is an anagram indicator.
'later' with letters rearranged gives 'ALERT'.
'for' acts as a link.
(Other definitions for alert that I've seen before include "Vigilant, watchful" , "Wide awake and watchful" , "In state of watchfulness" , "Put on guard, warn" , "Warning signal" .)