It's coming now — a lot of odd ideas about oneself (4,4)
I believe the answer is:
here goes
'it's coming' is the definition.
I can't tell whether this defines the answer.
'now a lot of odd ideas about oneself' is the wordplay.
'now' becomes 'here' (I've seen this in other clues).
'a lot of odd ideas' becomes 's' (I am not sure about this - if you are sure you should believe this answer much more).
'about' means one lot of letters goes inside another.
'oneself' becomes 'ego' (I've seen this in another clue).
'here'+'s'='heres'
'heres' enclosing 'ego' is 'HERE GOES!'.
Can you help me to learn more?
(Other definitions for here goes that I've seen before include "I'm about to start" , "I'm about to begin - ready, steady . . . . . . . ." , "I'm starting" , "Gee horse (anag.)" , "Words spoken before start of rash action?" .)