A benefit one's not seen in discipline for youth (11)
I believe the answer is:
adolescence
'for youth' is the definition.
(adolescence is part of one's youth)
'a benefit one's not seen in discipline' is the wordplay.
I cannot really see how this works, but
'a' is found in the answer.
'benefit' could be 'dole' (informal term for a state benefits) and 'dole' is found within the answer.
This may be the basis of the clue (or it may be nonsense).
Can you help me to learn more?
(Other definitions for adolescence that I've seen before include "Period before adulthood" , "Period of strong growth" , "Transition to adulthood" , "Period of youth" , "Puberty" .)