Sound feature: one installed (5)
I believe the answer is:
noise
'sound' is the definition.
(a noise is a sound)
'feature one installed' is the wordplay.
'feature' becomes 'nose' (I've seen this before).
'one' becomes 'i' (Roman numeral).
'installed' is an insertion indicator.
'nose' placed around 'i' is 'NOISE'.
(Other definitions for noise that I've seen before include "Virgil's birthplace" , "Row" , "Kind of pollution" , "Unwelcome sound" , "Unstructured sound" .)