Singer, but for one vocal inflection (8)
I believe the answer is:
baritone
'singer' is the definition.
(I know that baritone is a type of singer)
'but for one vocal inflection' is the wordplay.
'but' becomes 'bar' (both can mean 'excluding' or 'except').
'for one' becomes 'i' (I've seen this in other clues).
'vocal inflection' becomes 'tone' (I've seen this in another clue).
'bar'+'i'+'tone'='BARITONE'
(Other definitions for baritone that I've seen before include "Male singer between tenor and bass" , "Male voice with deep register" , "Adult male singing voice" , "Male singer in boater, strangely" , "Male singer looks odd in boater" .)