Many say it's untidy (7)
I believe the answer is:
clutter
'many' is the definition.
(thesaurus)
'say it's untidy' is the wordplay.
I cannot quite see how this works, but
'say' could be 'utter' (to utter something is to say or speak it) and 'utter' is located in the answer.
This explanation may well be incorrect...
Can you help me to learn more?
(Other definitions for clutter that I've seen before include "Jumble" , "Untidy mess" , "Confusion" , "Disorderly mess" , "Clog up" .)