Note books required in understanding narcissistic episode (3,4)
I believe the answer is:
ego trip
'narcissistic episode' is the definition.
'note books required in understanding' is the wordplay.
'note' becomes 'e' (musical note).
'books' becomes 'ot' (Old Testament).
'required in' means one lot of letters goes inside another.
'understanding' becomes 'grip'.
'ot' inserted within 'grip' is 'gotrip'.
'e'+'gotrip'='EGO TRIP'
(Other definitions for ego trip that I've seen before include "Self-gratifying action" , "Got ripe (anag.)" , "One's self-importance is boosted by it" , "self-centred indulgence" , "Exercise in self-indulgence" .)