Ensured one would have no more negative thoughts? (9,4,4)
I believe the answer is:
developed ones mind
'negative thoughts?' is the definition.
I don't know anything about this answer so I cannot tell whether it can be defined by this definition.
'ensured one would have no more' is the wordplay.
I cannot quite understand how this works, but
'one' could be 'i' (Roman numeral) and 'i' is found within the answer.
'would' could be 'd' (I've seen this in other clues) and 'd' is found within the answer.
'no' could be 'o' (resembles 0 - 'no' can mean 'zero') and 'o' is found within the answer.
'more' could be 'm' and 'm' is present in the answer.
This may be the basis of clue (or it may be nonsense).
Can you help me to learn more?