Like prison, you may not see it as a good thing! (6)
I believe the answer is:
poison
'thing' is the definition.
The answer and definition can be both human attributes as well as being singular nouns.
Perhaps they are linked in a way I don't understand?
'like prison you may not see it as a good' is the wordplay.
I cannot quite see how this works, but
'not' could be 'o' (I've seen this in other clues) and 'o' is present in the answer.
'as' could be 'so' (I've seen this in other clues) and 'so' is located in the answer.
'good' could be 'pi' (old-fashioned term for pious) and 'pi' is present in the leftover letters.
A single letter 'n' remains which might be clued in a way I don't see.
This may be the basis of the clue (or it may be nonsense).
Can you help me to learn more?
(Other definitions for poison that I've seen before include "Damaging stuff - drink?" , "[ADDER] 's defence" , "I spoon up the lethal substance" , "Meat for someone else" , "Corrupt" .)