The most common and most likely answer to this crossword clue is the 10 letter word REPRESSIVE
I've seen this crossword clue in The Daily Telegraph
R
E
P
R
E
S
S
I
V
E
More clues leading to the result REPRESSIVE
Buddy explains!

The straight part
We know that "being dictatorial" is the straight/definition part of the clue. The straight part is often a synonym or definition, in this case being dictatorial = repressive.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 REPRESSIVE mean?
REPRESSIVE adjective- Serving to repress or suppress; oppressive