Learner inside becoming keen on lecture (7-2)
I believe the answer is:
talking-to
'lecture' is the definition.
(synonyms)
'learner inside becoming keen on' is the wordplay.
'learner' becomes 'l' (as in a learner driver with L-plates on their car).
'inside' indicates putting letters inside.
'becoming keen on' becomes 'taking to' (to take to something is to become keen on it).
'l' put into 'takingto' is 'TALKING-TO'.
(Other definitions for talking-to that I've seen before include "Sharp reprimand (colloq.)" , "Dressing-down" , "Give someone a good ....... .. as a reproof" , "Criticism from one in authority" , "Session of criticism" .)