The most common and most likely answer to this crossword clue is the 9 letter word CONTAINED
I've seen this crossword clue in The Daily Telegraph
C
O
N
T
A
I
N
E
D
More clues leading to the result CONTAINED
Buddy explains!

The straight part
We know that "kept /under control" is the straight/definition part of the clue. The straight part is often a synonym or definition, in this case kept /under control = contained.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 CONTAINED mean?
CONTAINED verb- To hold inside.
- To include as a part.
- To put constraint upon; to restrain; to confine; to keep within bounds.
- (of a set etc.) To have as an element or subset.
- To restrain desire; to live in continence or chastity.
- Restricted in space.