Teach Europeans to hide old gold coin (7)
I believe the answer is:
educate
'teach' is the definition.
(to teach someone is to educate them)
'europeans to hide old gold coin' is the wordplay.
'europeans' becomes 'ee' (an abbreviation for European written twice).
'to hide' is an insertion indicator.
'old gold coin' becomes 'ducat' (old European coin).
'ee' enclosing 'ducat' is 'EDUCATE'.
(Other definitions for educate that I've seen before include "teaching style" , "Impart knowledge" , "Train, instruct" , "Enlighten" , "Teach - school" .)