Bows rot! (12)
I believe the answer is:
fiddlesticks
'bows' is the definition.
(fiddlestick is a kind of bow)
I don't understand how the rest of the clue works.
Can you help me to learn more?
(Other definitions for fiddlesticks that I've seen before include "Bilge" , "Rhubarb" , "Bows - nonsense" , "Bother!" , "tripe" .)