The most common and most likely answer to this crossword clue is the 8 letter word CROMWELL
I've seen this crossword clue in Independent
C
R
O
M
W
E
L
L
More clues leading to the result CROMWELL
- London's road protector
- English monarch with order, appropriately, for his enemy
- Civil War general‘s battery keeping Maryland’s capital in line
- Bringer of order against his king we will see here
- Replacing disc with electronic memory, showbiz mogul becomes dictator
- Oliver sees worm wriggling in retreat
- Old Republican, Romney halved weight in prison accommodation
- Councillor given honour by intensely austere leader
Buddy explains!
The straight part
We know that "dictator" is the straight/definition part of the clue. The straight part is often a synonym or definition, in this case dictator = cromwell.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.