Crazy comment presumably you can't get out of your head (6,4)

I believe the answer is:

mental note

I'm a little stuck... Click here to teach me more about this clue!

'presumably you can't get out of your head' is the definition.
I don't know anything about this answer so I cannot tell whether it can be defined by this definition.

'crazy comment' is the wordplay.
'crazy' becomes 'mental' (I've seen this before).
'comment' becomes 'note' (note is a kind of comment).
'mental'+'note'='MENTAL NOTE'

Can you help me to learn more?

I've seen this clue in the Irish Times (Crosaire) and the Irish Times.

Want a hint initially instead of a full solution? Install my app