The stamp of prestige (6)
I believe the answer is:
cachet
This clue is a double definition.
'the stamp' is the first definition.
(cachet is a kind of stamp)
'prestige' is the second definition.
(synonyms)
'of' acts as a link.
(Other definitions for cachet that I've seen before include "Prestige - seal of approval" , "Feature or quality conferring prestige" , "Kind of prestige, from France" , "Distinguishing mark or seal" , "French prestige or distinguishing mark" .)