Insult that's a f-facade (7)
I believe the answer is:
affront
'insult' is the definition.
('affront' can be a synonym of 'insult')
'a f-facade' is the wordplay.
'f-facade' becomes 'ffront' ('front' said with a stammer like 'facade' was; I've seen this before).
'a'+'ffront'='AFFRONT'
'that's' acts as a link.
(Other definitions for affront that I've seen before include "Action causing outrage or offence" , "Indignity" , "Rant off over insult" , "Open insult" , "Insult to one's face" .)