Bury the new trainee (6)
I believe the answer is:
intern
'trainee' is the definition.
(I've seen this before)
'bury the new' is the wordplay.
'bury' becomes 'inter' (synonyms).
'the new' becomes 'n' (common abbreviation eg NT for New Testament).
'inter'+'n'='INTERN'
(Other definitions for intern that I've seen before include "Deprive of freedom" , "Student" , "House officer" , "Houseman" , "Incarcerate without trial - a junior hospital doctor?" .)