For all to see in message, father's blunder (4,3)
I believe the answer is:
faux pas
'blunder' is the definition.
(I've seen this before)
'for all to see in message father's' is the wordplay.
'for all to see' becomes 'u' (universal dvd certificate).
'in' is an insertion indicator.
'message' becomes 'fax'.
'father's' becomes 'pa's' (pa can mean dad or father).
'u' inserted within 'fax' is 'faux'.
'faux'+'pas'='FAUX-PAS'
(Other definitions for faux pas that I've seen before include "Embarrassing blunder" , "Social gaffe" , "Social indiscretion" , "Social blunder" , "Bloomer" .)