Disturbed by Shaw play, throw plans into confusion (5,3,9)

I believe the answer is:

upset the applecart

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

'throw plans into confusion' is the definition.
I don't know anything about this answer so I can't tell whether this works.

'disturbed by shaw play' is the wordplay.
I cannot quite understand how this works, but
'disturbed' could be 'upset' (synonyms) and 'upset' is located in the answer.
'play' could be 'theapplecart' (I've seen this before) and 'theapplecart' is located in the answer.
No letters remain.
This explanation may well be incorrect...

Can you help me to learn more?

I've seen this clue in The Times.

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.