Singer appearing in Britten oratorio (5)
I believe the answer is:
tenor
'singer' is the definition.
(I know that tenor is a type of singer)
'in britten oratorio' is the wordplay.
'in' indicates a hidden word.
'TENOR' is hidden in the letters of 'britten oratorio'.
'appearing' is the link.
(Other definitions for tenor that I've seen before include "thread" , "Voice classification of Jose Carreras" , "Purport" , "theme" , "Male singing voice of high pitch" .)