Material used by writers — still, we hear! (10)
I believe the answer is:
stationery
'material used by writers' is the definition.
(pens, paper etc)
'still we hear' is the wordplay.
'still' becomes 'stationary' (both can mean immobile).
'we hear' shows a homophone (sound like).
'stationary' sounds like 'STATIONERY'.
(Other definitions for stationery that I've seen before include "Writing paper, etc" , "Treasury tags, for instance" , "Pens, pencils, paper etc" , "Writer's needs" , "Files etc" .)