A bit confusing that Rose, I'd not looked at it yet this weekend but it looked like a really long clue when you posted, you need to remember that not everyone has the crossword to hand and it helps if you put the exact clue up and amount of letters with any inserted that you already have. If your looking for a parse, then do the same and put the actual clue on one line and your question on another, it does help if you aint got the puzzle to look at and check
The clue is:
Twins misinterpreted PR - alas could not vote (6,3,6)
An anagram of PR alas could not X
(Castor and Pollux)