The most common and most likely answer to this crossword clue is the 5 letter word KRAAL
I've seen this crossword clue in The Times
K
R
A
A
L
More clues leading to the result KRAAL
- Frolic about, holding a pen
- Put up bird outside a native village
- Early riser takes turn protecting a village in Africa
- Enclosure, or area covered by singer making a comeback
- A bottomless lake and river development in South Africa
- Retiring flier must receive a settlement
- Early bird going up across area in African village
- Bird heading west across a South African village
- …village bird flipped embracing adult
- Set up joke about a village in Africa
Buddy explains!

The straight part
We know that "pen" is the straight/definition part of the clue. The straight part is often a synonym or definition, in this case pen = kraal.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 KRAAL mean?
KRAAL noun- In Central and Southern Africa, a small rural community.
- In Central and Southern Africa, a rural village of huts surrounded by a stockade.
- An enclosure for livestock.
- To enclose (livestock) within a kraal or stockade.