Use keyboard, yet needing revision without piano accurate in sound (9)
I believe the answer is:
typewrite
'use keyboard' is the definition.
(to typewrite is to type with a typewriter)
'yet needing revision without piano accurate in sound' is the wordplay.
'needing revision' indicates an anagram (I've seen this in other clues).
'without' is an insertion indicator ('without' can be similar in meaning to 'outside').
'piano' becomes 'p' (musical abbreviation).
'accurate' becomes 'right' (associated in meaning).
'in sound' shows a homophone (sound like).
'right' sounds like 'write'.
'yet' is an anagram of 'tye'.
'tye' enclosing 'p' is 'type'.
'type'+'write'='TYPEWRITE'
(Other definitions for typewrite that I've seen before include "Key characters" , "work in pool once" .)