The most common and most likely answer to this crossword clue is the 4 letter word CELL
I've seen this crossword clue in Independent
C
E
L
L
More clues leading to the result CELL
- Where prisoner waits to be flogged for speaking out?
- American mobile unit
- Source of power in small room
- Loudly auction off part of prison
- Small room‘s source of electric power
- Betray on radio tight-knit group
- Oboist originally leaving instrument in part of prison
- Reportedly make acceptable one-room dwelling
- Room with lines at back of church
- One-roomed dwelling to dispose of, reportedly
Buddy explains!

The straight part
We know that "part of prison" is the straight/definition part of the clue. The straight part is often a synonym or definition, in this case part of prison = cell.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 CELL mean?
CELL noun- A single-room dwelling for a hermit.
- A small monastery or nunnery dependent on a larger religious establishment.
- A small room in a monastery or nunnery accommodating one person.
- A room in a prison or jail for one or more inmates.
- Each of the small hexagonal compartments in a honeycomb.
- Any of various chambers in a tissue or organism having specific functions.
- The discal cell of the wing of a lepidopteran insect.
- Specifically, any of the supposed compartments of the brain, formerly thought to be the source of specific mental capacities, knowledge, or memories.
- A section or compartment of a larger structure.
- Any small dwelling; a remote nook, a den.
- A device which stores electrical power; used either singly or together in batteries; the basic unit of a battery.
- The basic unit of a living organism, consisting of a quantity of protoplasm surrounded by a cell membrane, which is able to synthesize proteins and replicate itself.
- A small thunderstorm, caused by convection, that forms ahead of a storm front.
- The minimal unit of a cellular automaton that can change state and has an associated behavior.
- In FreeCell-type games, a space where one card can be placed.
- A small group of people forming part of a larger organization, often an outlawed one.
- (communication) A short, fixed-length packet as in asynchronous transfer mode.
- (communication) A region of radio reception that is a part of a larger radio network.
- A three-dimensional facet of a polytope.
- The unit in a statistical array (a spreadsheet, for example) where a row and a column intersect.
- The space between the ribs of a vaulted roof.
- A cella.
- An area of an insect wing bounded by veins
- To place or enclose in a cell.
- A cellular phone.