The most common and most likely answer to this crossword clue is the 14 letter word PENITENTIARIES
I've seen this crossword clue in The Daily Telegraph
P
E
N
I
T
E
N
T
I
A
R
I
E
S
Buddy explains!
The straight part
We know that "prisons" is the straight/definition part of the clue. The straight part is often a synonym or definition, in this case prisons = penitentiaries.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 PENITENTIARIES mean?
PENITENTIARIES noun- A state or federal prison for convicted felons; (broadly) a prison.
- A priest in the Roman Catholic Church who administers the sacrament of penance.
- One who prescribes the rules and measures of penance.
- One who does penance.
- A small building in a monastery, or a part of a church, where penitents confessed.
- An office of the papal court which examines cases of conscience, confession, absolution from vows, etc., and delivers decisions, dispensations, etc.; run by a cardinal called the Grand Penitentiary who is appointed by the pope.
- An officer in some dioceses since 1215, vested with power from the bishop to absolve in cases reserved to him.