Four year US President which can be a source of irritation (3-4)

I believe the answer is:

ivy-bush

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

'can be a source of irritation' is the definition.
I know nothing about this answer so I cannot tell whether this works.

'four year us president' is the wordplay.
'four' becomes 'IV' (Roman numerals).
'year' becomes 'y'.
'us president' becomes 'bush' (George H W Bush or George W Bush).
'iv'+'y'+'bush'='IVY-BUSH'

'which' acts as a link.

Can you help me to learn more?

I've seen this clue in The Independent.

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.