The most common and most likely answer to this crossword clue is the 6 letter word EX-CON
I've seen this crossword clue in The Guardian
E
X
-
C
O
N
More clues leading to the result EX-CON
- Is one’s time up in Labour now, then?
- One whose time is done in City, working with cross to bear
- Former Tory, such as Jeffrey Archer
- Criminal once old and blue
- One’s time has passed, a Tory no more?
- About ninety, one exercising, one having done a stretch?
- One’s no longer inside E10 with constable
- One having cooler experience after leaving the Tory Party?
- One now unrestrained in sex conversation
- Former Tory who used to be in prison
Buddy explains!

The straight part
We know that "who used to be in prison" is the straight/definition part of the clue. The straight part is often a synonym or definition, in this case who used to be in prison = ex-con.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.
What does EX-CON mean?
EX-CON noun- A former prisoner.