Sound car outstanding originally (5)
I believe the answer is:
audio
'sound' is the definition.
('audio' can be a synonym of 'sound')
'car outstanding originally' is the wordplay.
'car' becomes 'audi' (audi is a german car brand).
'originally' suggests taking the first letters.
The initial letter of 'outstanding' is 'o'.
'audi'+'o'='AUDIO'
(Other definitions for audio that I've seen before include "TV sound" , "What is heard" , "Television sound" , "- Tape; - typist" , "Reproduced sound" .)