I don’t know when solver has setter trapped? (5,3,2)

'trapped?' is the definition.
I know nothing about this answer so I cannot tell whether it can be defined by this definition.

'i don't know when solver has setter' is the wordplay.
I cannot really see how this works, but
'i' could be 'ego' ('I' in Latin) and 'ego' is found in the answer.
'solver' could be 'you' (the person solving the crossword) and 'you' is found within the answer.
'setter' could be 'me' (the setter of the clue) and 'me' is present in the answer.
This explanation may well be incorrect...

Can you help me to learn more?