Crossword Genius

The practice of looking after number one? (7)

Ross

I believe the answer is:

urology

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

This could be a double definition.

'the practice' is the first definition.
The definition and answer can be both related to thinking as well as being singular nouns.
Perhaps they are linked in a way I don't understand?

'looking after number one?' is the second definition.
Although both the answer and definition are singular nouns, I don't see how one could define the other.

'of' is the link.

Can you help me to learn more?

I've seen this clue in The Independent.
Want a hint initially instead of a full solution? Install my app