Intolerable (6,3,4)
I believe the answer is:
beyond the pale
'intolerable' is the definition.
(I've seen this before)
This is the entire clue.
(Other definitions for beyond the pale that I've seen before include "Outside the bounds of acceptable behaviour" , "to be completely colourless?" , "Only understood by tanned people?" , "Socially unacceptable" , "Totally unacceptable" .)