Teaching session (6)
'teaching session' is the definition.
(I've seen this in another clue)
This is all the clue.
(Other definitions for lesson that I've seen before include "Spell of instruction" , "Piece of instruction" , "Church reading" , "Unit of instruction" , "Sermon or example" .)
(Other definitions for seminar that I've seen before include "Study group on specific subject" , "Working meeting in College" , "Student discussion group - remains (anag)" , "Discussion meeting" , "Training conference" .)
'teaching session' is the definition.
(I've seen this before)
This is all the clue.
(Other definitions for tutorial that I've seen before include "Session of intensive teaching to an individual or small group" , "Teaching session for a small number of students" , "Conference" , "Session with a private instructor" , "Period of teaching as from college lecturer" .)