Standard fit for lesson (7)
I believe the answer is:
parable
'lesson' is the definition.
(I've seen this before)
'standard fit' is the wordplay.
'standard' becomes 'par' (standard of play in golf).
'fit' becomes 'able' (similar in meaning).
'par'+'able'='PARABLE'
'for' acts as a link.
(Other definitions for parable that I've seen before include "Story with ethical point" , "Meaningful story" , "scripture lesson" , "Gospel story" , "Story illustrating moral lesson" .)