So long, notice that is for all to see (5)
I believe the answer is:
adieu
'so long' is the definition.
('adieu' can be a synonym of 'so long')
'notice that is for all to see' is the wordplay.
'notice' becomes 'ad'.
'that is' becomes 'ie' ('i.e.' can be a synonym of 'that is').
'for all to see' becomes 'u' (universal dvd certificate).
'ad'+'ie'+'u'='ADIEU'
(Other definitions for adieu that I've seen before include "Goodbye, monsieur" , "Cheerio" , "Ciao, in French" , "Goodbye, madame" , "I'm going" .)