One such as Caiaphas: when drunk he is right to keep quiet (4,6)
I believe the answer is:
high priest
'one such as caiaphas when drunk he is right to keep quiet' is the definition.
The answer is a person as well as being a singular noun. This is suggested by the definition.
'drunk he is right to keep quiet' is the wordplay.
'drunk' indicates an anagram.
'to keep' is an insertion indicator.
'quiet' becomes 'p' (music symbol for 'piano', ie soft or quiet).
'he'+'is'+'right'='heisright'
'heisright' with letters rearranged gives 'highriest'.
'highriest' going around 'p' is 'HIGH PRIEST'.
Can you help me to learn more?
(Other definitions for high priest that I've seen before include "Ecclesiastical dignitary" , "Chief religious official" , "cult leader" , "Senior clergyman" , "Not how this minister" .)