Old coin found in East European train (7)
I believe the answer is:
educate
'train' is the definition.
('educate' can be a synonym of 'train')
'old coin found in east european' is the wordplay.
'old coin' becomes 'ducat' (I've seen this before**).
'found in' is an insertion indicator.
'east' becomes 'e' ('E' can be a synonym of 'east').
'european' becomes 'e' (abbreviation e.g. EU).
'e'+'e'='ee'
'ducat' put inside 'ee' is 'EDUCATE'.
(Other definitions for educate that I've seen before include "teaching style" , "Bring up" , "School, train" , "Impart knowledge" , "Teach - instruct" .)