Teach English repeatedly about old money (7)
I believe the answer is:
educate
'teach' is the definition.
(to teach someone is to educate them)
'english repeatedly about old money' is the wordplay.
'english' becomes 'E' (abbreviation).
'repeatedly' shows that letters should be duplicated.
'about' means one lot of letters goes inside another.
'old money' becomes 'ducat' (historical type of coin).
'e' duplicated is 'ee'.
'ee' enclosing 'ducat' is 'EDUCATE'.
(Other definitions for educate that I've seen before include "Tutor" , "Enlighten" , "Train, instruct" , "what teacher should do, to be effective" , "Impart learning" .)