Upset voter rattled ballot box - Lib Dem leader? (10)

I believe the answer is:

overturned

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

'upset' is the definition.
(synonyms)

'voter rattled ballot box lib dem leader?' is the wordplay.
'rattled' is an anagram indicator.
'ballot box' becomes 'urn' (urn can mean a ballot box in some countries).
'lib' becomes 'e' (I am not sure about this - if you are sure you should believe this answer much more).
'leader?' suggests taking the first letters (I've seen 'leader' mean this).
The first letter of 'dem' is 'd'.
'voter' is an anagram of 'overt'.
'overt'+'urn'+'e'+'d'='OVERTURNED'

Can you help me to learn more?

(Other definitions for overturned that I've seen before include "Placed upside down" , "Reversed (a legal decision)" , "Capsized" .)

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.