Learned river flows back, covering ancient coin (8)
I believe the answer is:
educated
'learned' is the definition.
(educating is a kind of learning)
'river flows back covering ancient coin' is the wordplay.
'river' becomes 'dee' (River Dee).
'flows back' shows that the letters should be reversed in order.
'covering' indicates putting letters inside.
'ancient coin' becomes 'ducat' (I've seen this before).
'dee' backwards is 'eed'.
'eed' placed around 'ducat' is 'EDUCATED'.
(Other definitions for educated that I've seen before include "Schooled, trained" , "Erudite" , "Cultivated, knowledgeable" , "Maybe enlightened" , "Having completed schooling, well informed" .)