Guitarist's finale duckwalk after break is rubbish! (7)
I believe the answer is:
twaddle
'is rubbish' is the definition.
(both can mean nonsense)
I cannot understand how the remainder of the clue works.
Can you help me to learn more?
(Other definitions for twaddle that I've seen before include "Claptrap" , "Rubbish" , "Trivial/foolish speech" , "Foolish talk" , "Poppycock" .)