Knowledge passed down about current in continental river (5)
I believe the answer is:
loire
'continental river' is the definition.
(river of France)
'knowledge passed down about current' is the wordplay.
'knowledge passed down' becomes 'lore'.
'about' means one lot of letters goes inside another.
'current' becomes 'i' (symbol for electric current).
'lore' placed around 'i' is 'LOIRE'.
'in' is the link.
(Other definitions for loire that I've seen before include "flower abroad" , "flower found amid vineyards" , "Longest French river" , "Current French" , "valley famous for its wines" .)