Simplicity without any meaning by the sound of it (9)
I believe the answer is:
innocence
'simplicity' is the definition.
(thesaurus)
'without any meaning by the sound of it' is the wordplay.
I cannot really see how this works, but
'without' could be 'no' and 'no' is present in the answer.
'it' could be 'e' ('e' can mean 'electronic' which is similar to 'IT') and 'e' is found in the answer.
This explanation may well be incorrect...
Can you help me to learn more?
(Other definitions for innocence that I've seen before include "''Songs of ... and Experience'' (William Blake)" , "clean?" , "subject of Blake's songs" , "Blamelessness" , "Freedom from guilt" .)