A warning of later development (5)
I believe the answer is:
alert
'a warning' is the definition.
(I know that alert is a type of warning)
'later development' is the wordplay.
'development' indicates anagramming the letters.
'later' with letters rearranged gives 'ALERT'.
'of' is the link.
(Other definitions for alert that I've seen before include "Watchful, quick-thinking" , "Wakeful, observant" , "Watchfully awake" , "Signal danger" , "Intellectually active" .)