Cricketer's run, so long (3)
I believe the answer is:
bye
I believe this clue is a double definition.
'cricketer's run' is the first definition.
(type of run in cricket)
'so long' is the second definition.
(synonyms)
(Other definitions for bye that I've seen before include "I'm off" , "Get one to advance to the next round without playing an opponent" , "Stay out of round" , "Farewell! (informal)" , "Run scored in cricket from a ball that passes batman" .)