The most common and most likely answer to this crossword clue is the 5 letter word ROMAN
I've seen this crossword clue in The Times
R
O
M
A
N
More clues leading to the result ROMAN
Buddy explains!

The straight part
We know that "Eg Caesar" is the straight/definition part of the clue. The straight part is often a synonym or definition, in this case eg caesar = roman.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 ROMAN mean?
ROMAN noun- One of the main three types used for the Latin alphabet (the others being italics and blackletter), in which the ascenders are mostly straight.
- A novel.
- (of type) upright, as opposed to italic
- (of text) of or related to the Latin alphabet