Mr Pirrip's sorry about at least one revelation (8)
I believe the answer is:
epiphany
'one revelation' is the definition.
(I've seen this before)
'mr pirrip's sorry about at least' is the wordplay.
I cannot really see how this works, but
'mr' could be 'pip' and 'pip' is found within the answer.
'about' could be 'a' (abbreviation in Chambers) and 'a' is found in the answer.
This may be the basis of clue (or it may be nonsense).
Can you help me to learn more?
(Other definitions for epiphany that I've seen before include "Church festival" , "Moment of sudden revelation (involving three wise men from the east?)" , "Christian festival of Magi visiting Chirst, celebrated on 6th January" , "A devine manifestation" , "Christian feast of showing Christ to Magi" .)