Influence of rock? (4)
I believe the answer is:
sway
I believe this is a double definition.
'influence' is the first definition.
(I know this)
'rock?' is the second definition.
(I know that rock can be written as sway)
'of' acts as a link.
(Other definitions for sway that I've seen before include "Control" , "Swing - lean - persuade" , "Strong influence" , "Rock to and fro" , "Influence; rule" .)