The most common and most likely answer to this crossword clue is the 7 letter word DUNGEON
D
U
N
G
E
O
N
More clues leading to the result DUNGEON
- Waste material one’s thrown in underground cell
- Place of confinement debt collector has no say about
- Debt-collector gone mad in underground cell
- Animal droppings disturbed one in cell?
- Keep prisoners in it
- Horse and dope found around old prison cell
- Muck over time found in subterraneous accommodation
- Waste time in oubliette
- Done messing with gun: prison the result
- Place for prisoner that's done for misbehaving with gun?
Buddy explains!

The straight part
We know that "Keep" is the straight/definition part of the clue. The straight part is often a synonym or definition, in this case keep = dungeon.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 DUNGEON mean?
DUNGEON noun- An underground prison or vault, typically built underneath a castle.
- The main tower of a motte or castle; a keep or donjon.
- A shrewd person.
- (games) An area inhabited by enemies, containing story objectives, treasure and bosses.
- (BDSM) A room dedicated to sadomasochistic sexual activity.
- To imprison in a dungeon.