The most common and most likely answer to this crossword clue is the 6 letter word TYRANT
I've seen this crossword clue in The Times
T
Y
R
A
N
T
More clues leading to the result TYRANT
- Oppressor's extremely tacky tirade
- Cruel ruler’s extremely tawdry outburst
- Authoritarian deputy ran the shows
- Despot’s extremely timely tirade
- Autocrat, Russia’s leader in unusually natty clothing
- Bully fled in Toyota, ejecting regular occupants
- Soldier, perhaps, under war god and despot
- Authoritarian type regularly stays talking crosswords
- Tense year with soldier becoming despot
- Despot‘s terribly hollow violent speech
Buddy explains!

The straight part
We know that "Authoritarian" is the straight/definition part of the clue. The straight part is often a synonym or definition, in this case authoritarian = tyrant.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 TYRANT mean?
TYRANT noun- A usurper; one who gains power and rules extralegally, distinguished from kings elevated by election or succession.
- Any monarch or governor.
- A despot; a ruler who governs unjustly, cruelly, or harshly.
- (by extension) Any person who abuses the power of position or office to treat others unjustly, cruelly, or harshly.
- (by extension) A villain; a person or thing who uses strength or violence to treat others unjustly, cruelly, or harshly.
- The tyrant bird, members of the family Tyrannidae, which often fight or drive off other birds which approach their nests.
- To act like a tyrant; to be tyrannical.
- To tyrannize.
- Tyrannical, tyrannous; like, characteristic of, or in the manner of a tyrant.