Every so often, permit child child a joint (6)
I believe the answer is:
prison
'child a joint' is the definition.
I can't tell whether this definition defines the answer.
'every so often permit child' is the wordplay.
'every so often' indicates alternate letters.
'child' becomes 'son' (son is a kind of child).
The alternating letters of 'permit' are 'pri'.
'pri'+'son'='PRISON'
Can you help me to learn more?
(Other definitions for prison that I've seen before include "No rips (anag)" , "Jail" , "porridge" , "Eg, Wormwood Scrubs" , "punishment" .)