Stupid suggestion, lacking new musical direction (10)
I believe the answer is:
diminuendo
'musical direction' is the definition.
I know that 'musical' relates to this answer. I also know that both the answer and definition are singular nouns
'stupid suggestion lacking new' is the wordplay.
I cannot really understand how this works, but
'stupid' could be 'dim' (similar in meaning) and 'dim' is found within the answer.
'new' could be 'n' (common abbreviation eg NT for New Testament) and 'n' is present in the answer.
This explanation may well be incorrect...
Can you help me to learn more?
(Other definitions for diminuendo that I've seen before include "losing force" , "Letting sound fade away" , "volume is to be cut" , "Decrease in loudness" , "becoming quieter" .)