Low noise (6)
I believe the answer is:
rumble
'low noise' is the definition.
(I've seen this in another clue)
This is the entire clue.
(Other definitions for rumble that I've seen before include "Sound of thunder or a hungry stomach - discover (plans)" , "Harlem gangs might" , "Make a low noise" , "Tummy sound - discover (an illicit activity)" , "Find out the truth" .)