The most common and most likely answer to this crossword clue is the 5 letter word CLINK
I've seen this crossword clue in The Times
C
L
I
N
K
More clues leading to the result CLINK
- Conservative connection in prison
- Caught by part of chain in prison
- Cooler climate’s likely in North Korea initially
- Sound prison
- Nick, college joiner
- Noise made by chains in prison
- Caught with joint in prison
- Caught having joint in prison
- Part of chain put on Charlie in prison
- Sound of keys rattling in prison
Buddy explains!

The straight part
We know that "prison" is the straight/definition part of the clue. The straight part is often a synonym or definition, in this case prison = clink.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 CLINK mean?
CLINK noun- The sound of metal on metal, or glass on glass.
- To make a clinking sound; to make a sound of metal on metal or glass on glass; to strike materials such as metal or glass against one another.
- To rhyme.
- A prison.
- Stress cracks produced in metal ingots as they cool after being cast.
- To clinch; to rivet.