Old-time singer and performers meeting retired sailor at end of oratorio (8)
I believe the answer is:
castrato
'old-time singer' is the definition.
'performers meeting retired sailor at end of oratorio' is the wordplay.
'performers' becomes 'cast' (I've seen this before).
'meeting' is a charade indicator (letters next to each other).
'retired' shows that the letters should be reversed in order.
'sailor' becomes 'tar' (tar is a kind of sailor**).
'at end of' indicates one should take the final letters.
The final letter of 'oratorio' is 'o'.
'tar' backwards is 'rat'.
'cast'+'rat'+'o'='CASTRATO'
'and' acts as a link.
(Other definitions for castrato that I've seen before include "one with no stones" , "this singer couldn't reproduce!" , "Former high male singer" , "Emasculated male singer with a soprano or alto voice" , "Male singer operated on before puberty to retain his soprano voice" .)