The most common and most likely answer to this crossword clue is the 8 plus 6 letter word HUMPHREY BOGART
I've seen this crossword clue in Independent
H
U
M
P
H
R
E
Y
B
O
G
A
R
T
More clues leading to the result HUMPHREY BOGART
Buddy explains!
The straight part
We know that "Actor" is the straight/definition part of the clue. The straight part is often a synonym or definition, in this case actor = humphrey bogart.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.