The most common and most likely answer to this crossword clue is the 8 plus 5 letter word FLOATING VOTER
I've seen this crossword clue in The Times
F
L
O
A
T
I
N
G
V
O
T
E
R
More clues leading to the result FLOATING VOTER
- But one may not be at sea in one’s varying choices
- One crosses indecisively from side to side!
- Government to fail – team out in reshuffle, one by no means partisan
- One doesn’t know where to cross
- One moving from party to party?
- Elector all at sea?
- Elector not sure to be forgiven a lot, possibly including treason without cause
- To travel in fog is stupid for indecisive citizen
- One is going from one party to another — got travel info somehow
- One undertaking crossing at sea?
Buddy explains!
The straight part
We know that "But one may not be at sea in one’s varying choices" is the straight/definition part of the clue. The straight part is often a synonym or definition, in this case but one may not be at sea in one’s varying choices = floating voter.The cryptic/wordplay part
In cryptic crossword there's often an wordplay/cryptic part as well.This part involves a more complex hint, such as an anagram, homophone, hidden word, etc.
Sadly, We don't have an explanation for this specific crossword clue yet.