Thoughts seen in mirror? (11)

'thoughts' is the definition.
(reflection is a kind of thought)

'in mirror?' is the wordplay.
I cannot really understand how this works, but
'mirror?' could be 'reflect' (mirror can mean to reflect) and 'reflect' is present in the answer.
The remaining letters 'ions' is a valid word which might be clued in a way I don't understand.
This may be the basis of the clue (or it may be nonsense).

'seen' acts as a link.

Can you help me to learn more?