The most common and most likely answer to this crossword clue is the 11 letter word TRIUMVIRATE
I've seen this crossword clue in The Times
T
R
I
U
M
V
I
R
A
T
E
Buddy explains!
The straight part
We know that "coalition in power" is the straight/definition part of the clue. The straight part is often a synonym or definition, in this case coalition in power = triumvirate.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 TRIUMVIRATE mean?
TRIUMVIRATE noun- An official group of three people, especially a ruling council of three men and particularly two such councils in Roman history.