Making appointment for unruly child genius - one I forgot (10)

'making appointment' is the definition.
The definition and answer can be both acts as well as being singular nouns.
Maybe there's a link between them I don't understand?

'unruly child genius one i forgot' is the wordplay.
I cannot quite see how this works, but
'child' could be 'ch' (abbreviation for child) and 'ch' is located in the answer.
'one' could be 'i' (Roman numeral) and 'i' is located in the answer.
This explanation may well be incorrect...

'for' is the link.

Can you help me to learn more?