See you later! (3)
I believe the answer is:
bye
'see you later' is the definition.
(I've seen this in another clue)
This is all the clue.
(Other definitions for bye that I've seen before include "Cricketing extra" , "Get one to advance to the next round without playing an opponent" , "So long" , "Run not off bat" , "I'm off" .)