Partner of Crackle and Pop (4)
I believe the answer is:
snap
'partner of crackle and pop' is the definition.
(I've seen this in another clue)
This is the entire clue.
(Other definitions for snap that I've seen before include "unexpected? > Same here!" , "Quick photograph - impression" , "Spell of cold weather and card game" , "Break with a crack" , "Break sharply like dry twig" .)