A lesson without standards (6)
I believe the answer is:
amoral
'without standards' is the definition.
I can't tell whether this definition defines the answer.
'a lesson' is the wordplay.
'lesson' becomes 'moral' (as in the moral of the story).
'a'+'moral'='AMORAL'
Can you help me to learn more?
(Other definitions for amoral that I've seen before include "Lacking any ethical standards" , "Ignoring what's right and wrong" , "Without sense of right and wrong" , "Lacking sense of decency" , "without guiding principles" .)