Tutorial (6)
'tutorial' is the definition.
(I've seen this before)
This is the entire clue.
(Other definitions for lesson that I've seen before include "15 down period" , "Single period of instruction" , "Bible passage read as part of a church service" , "Piece of instruction" , "Teaching period" .)
'tutorial' is the definition.
This is all the clue.
(Other definitions for seminar that I've seen before include "Group discussing" , "University discussion" , "Marines (anag.)" , "workshop" , "Training meeting" .)