Indulgent, allowed the nine incarcerated to go free (7)
I believe the answer is:
lenient
'indulgent' is the definition.
(synonyms)
'allowed the nine incarcerated to go free' is the wordplay.
I cannot quite understand how this works, but
'the' could be 't' (the is pronounced as a 't' sound in some dialects) and 't' is present in the answer.
an anagram of 'nine' is 'nien' which is within the answer.
This explanation may well be incorrect...
Can you help me to learn more?
(Other definitions for lenient that I've seen before include "Easy, soft" , "Forgiving, gentle" , "Not severe in punishing" , "Merciful or easygoing" , "Tolerant, merciful" .)