Youth essentially permitted to vent (6)
I believe the answer is:
outlet
'to vent' is the definition.
(I've seen this in another clue)
'youth essentially permitted' is the wordplay.
'essentially' indicates the central letters.
'permitted' becomes 'let' (to let something happen is to permit it).
The centre of 'youth' is 'out'.
'out'+'let'='OUTLET'
(Other definitions for outlet that I've seen before include "Passage through which things can escape" , "Maths relationship" , "Vent, means of escape" , "Shop (retail)" , "Opening, vent." .)