Singer taking part in Britten oratorio (5)
I believe the answer is:
tenor
'singer' is the definition.
(I know that tenor is a type of singer)
'part in britten oratorio' is the wordplay.
'part in' says the answer is hidden in the clue.
'TENOR' is hidden in the letters of 'britten oratorio'.
'taking' is the link.
(Other definitions for tenor that I've seen before include "Male voice (one of three?)" , "Pitch range" , "General meaning of an utterance" , "Eg, Placido Domingo" , "character" .)