Unmelodious (8)
I believe the answer is:
tuneless
'unmelodious' is the definition.
(I know that unmelodious can be written as tuneless)
This is all the clue.
(Other definitions for tuneless that I've seen before include "Unpleasant to hear" , "Unmelodious" , "Not melodious" , "harsh" , "Like some whistling" .)