The most common and most likely answer to this crossword clue is the 10 letter word SUPERGIANT
I've seen this crossword clue in Financial Times
S
U
P
E
R
G
I
A
N
T
More clues leading to the result SUPERGIANT
Buddy explains!
The straight part
We know that "Filled with power, great sun I suspect?" is the straight/definition part of the clue. The straight part is often a synonym or definition, in this case filled with power, great sun i suspect? = supergiant.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 SUPERGIANT mean?
SUPERGIANT noun- A very large star having a mass between 10 and 70 solar masses.