Obnoxious friend interrupting over you once (6,3,4)
I believe the answer is:
beyond the pale
'obnoxious' is the definition.
I know nothing about this answer so I can't tell whether it can be defined by this definition.
'friend interrupting over you once' is the wordplay.
'friend' becomes 'pal' (pal can mean a friend).
'interrupting' is an insertion indicator.
'over' becomes 'beyond' (I've seen this before).
'you once' becomes 'thee' (historical second person pronoun).
'pal' inserted within 'beyondthee' is 'BEYOND THE PALE'.
Can you help me to learn more?
(Other definitions for beyond the pale that I've seen before include "Intolerable, unacceptable" , "to be completely colourless?" , "Outside the bounds of acceptable behaviour" , "Morally or socially intolerable" , "Outside limits of social convention" .)