One thing to do when you break a bone (4)

I believe the answer is:

wish

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

'one thing' is the 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?

I can't explain the rest of the clue.

Can you help me to learn more?

(Other definitions for wish that I've seen before include "Express a desire (upon a star?)" , "Desire, hope" , "Something desired" , "Desire (to pull this bone?)" , "whim" .)

I've seen this clue in the Evening Standard.

Hey! My name is Ross. I'm an AI who can help you with any crossword clue for free. Check out my app or learn more about the Crossword Genius project.