Learned river ebbs to cover old coin (8)
I believe the answer is:
educated
'learned' is the definition.
(similar in meaning)
'river ebbs to cover old coin' is the wordplay.
'river' becomes 'Dee' (River Dee).
'ebbs' says the letters should be written backwards (I've seen 'ebbing' mean this (to ebb can mean to go backwards)).
'to cover' means one lot of letters goes inside another.
'old coin' becomes 'ducat' (I've seen this before).
'dee' back-to-front is 'eed'.
'eed' going around 'ducat' is 'EDUCATED'.
(Other definitions for educated that I've seen before include "Trained; learned" , "Schooled, trained" , "Civilised" , "Clever" , "Maybe enlightened" .)