Writing stuff fixed, by the sound of it (10)
I believe the answer is:
stationery
'writing stuff' is the definition.
(materials and equipment used for writing)
'fixed by the sound of it' is the wordplay.
'fixed' becomes 'stationary' (synonyms).
'by the sound of it' shows a homophone (sound like).
'stationary' is a homophone of 'STATIONERY'.
(Other definitions for stationery that I've seen before include "Various items in paper" , "Pens, pencils, paper etc" , "Files etc" , "The papers, etc" , "Materials needed for writing" .)