Aftertaste of a plucking sound (5)
I believe the answer is:
twang
I believe this clue is a double definition.
'aftertaste' is the first definition.
'a plucking sound' is the second definition.
(I've seen this before)
'of' acts as a link.
(Other definitions for twang that I've seen before include "Nasal or musical sound" , "Distinctive nasal style of pronunciation" , "Nasal accent" , "ringing sound" , "Sound of plucked string (or certain dialects)" .)