The most common and most likely answer to this crossword clue is the 10 letter word IMPRISONED
I've seen this crossword clue in Financial Times
I
M
P
R
I
S
O
N
E
D
More clues leading to the result IMPRISONED
- Given time, one’s inclined to accept one’s daughter
- Surprisingly dim person I locked up
- Put away for safety?
- I am meeting criminal person I’d put behind bars
- Behind bars — dim person sadly getting one captured
- Put away demon fiddle rosined
- Little devil on wild ride — relative intervening is shut up
- Politician held in derision, possibly as Archer was?
- I’m forced to go round working behind bars
- Derision cast about politician behind bars
Buddy explains!

The straight part
We know that "locked up" is the straight/definition part of the clue. The straight part is often a synonym or definition, in this case locked up = imprisoned.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 IMPRISONED mean?
IMPRISONED verb- To put in or as if in prison; confine.