The most common and most likely answer to this crossword clue is the 9 letter word CASTELLAN
I've seen this crossword clue in The Guardian
C
A
S
T
E
L
L
A
N
More clues leading to the result CASTELLAN
- Keep manager, outstanding almost to the end, in prison
- Governor's girl in prison
- Beer in can? That’s a keeper
- Keeper of fortification filling tin with lager
- For one running keep tin of beer?
- Governor of fortress imprisons woman in metal container
- Housekeeper perhaps, introduces lady to background network
Buddy explains!
The straight part
We know that "Keeper of fortificatio" is the straight/definition part of the clue. The straight part is often a synonym or definition, in this case keeper of fortificatio = castellan.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 CASTELLAN mean?
CASTELLAN noun- The governor or caretaker of a castle or keep.