Learned line? Say again (8)
I believe the answer is:
literate
'learned' is the definition.
('literate' can be a synonym of 'learned')
'line? say again' is the wordplay.
'line?' becomes 'l'.
'say again' becomes 'iterate' (I've seen this before).
'l'+'iterate'='LITERATE'
(Other definitions for literate that I've seen before include "Well versed in books" , "version of 'speed of light'?" , "Relate it, being well read" , "well expressed" , "Scholarly" .)