Vibrations (6)
'vibrations' is the definition.
(I know this)
This is the entire clue.
(Other definitions for tremors that I've seen before include "Err most (anag.)" , "Quivers" , "Small earthquakes" , "Quakes" , "Vibrations" .)
(Other definitions for throbs that I've seen before include "Beats as a pulse" , "Beats with persistent rhythm, as heart does" , "Pulsates like heart" , "Beats like the heart" , "Pounds" .)