Graduate tries replacing masters (7)
I believe the answer is:
maestri
'masters' is the definition.
('maestro' can be a synonym of 'master')
'graduate tries replacing' is the wordplay.
'graduate' becomes 'ma' (abbreviation for Master of Arts**).
'replacing' indicates anagramming the letters (placing again).
'tries' is an anagram of 'estri'.
'ma'+'estri'='MAESTRI'
(Other definitions for maestri that I've seen before include "Distinguished musicians" , "Top conductors" , "Eminent musical conductors" , "leading musicians" , "Famous conductors" .)