"Didn't I warn you?” (3)
I believe the answer is:
see
'didn't i warn you?' is the definition.
(I've seen this in another clue)
This is the entire clue.
(Other definitions for see that I've seen before include "Consider; diocese" , "Perceive with eyes or mind" , "Norwich, for example" , "Meet (someone) socially" , "Discern visually" .)