Screw up half mile post (7)

I believe the answer is:

mistake

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

'screw up' is the definition.
The definition and answer can be both acts as well as being singular nouns.
Maybe you can see an association between them that I don't see?

'half mile post' is the wordplay.
'half' means to take half the letters.
'post' becomes 'stake' (synonyms).
'mile' halved is 'mi'.
'mi'+'stake'='MISTAKE'

Can you help me to learn more?

(Other definitions for mistake that I've seen before include "Wrong action or judgment" , "Fault" , "Slip" , "Oversight" , "Error" .)

I've seen this clue in the Sydney Morning Herald.

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.