Insult with impact one has to countenance? (4,2,3,4)
I believe the answer is:
slap in the face
'insult' is the definition.
(I've seen this before)
'with impact one has to countenance?' is the wordplay.
'with' says to put letters next to each other.
'impact' becomes 'slap' (slap is a kind of impact).
'one has to' becomes 'inthe' (I can't explain this - if you can you should give a lot more credence to this answer).
'countenance?' becomes 'face' (countenance is a kind of face).
'slap' next to 'inthe' is 'slapinthe'.
'slapinthe'+'face'='SLAP IN THE FACE'
(Other definitions for slap in the face that I've seen before include "the result of stupidly eating pancake?" , "Unexpected affront" , "Insult" , "Unexpected rejection" .)