Annoy with very quiet wave (6)
I believe the answer is:
ripple
'wave' is the definition.
(I know that ripple is a type of wave)
'annoy with very quiet' is the wordplay.
'annoy' becomes 'rile' (synonyms).
'with' is an insertion indicator.
'very quiet' becomes 'pp' (musical abbreviation for pianissimo).
'rile' placed around 'pp' is 'RIPPLE'.
(Other definitions for ripple that I've seen before include "A small wave, or a gentle sound as of laughter" , "Slight disturbance on surface of lake" , "Small wave on the surface of a liquid" , "Type of ice cream with coloured syrup" , "undulation" .)