The most common and most likely answer to this crossword clue is the 10 letter word SOUBRIQUET
I've seen this crossword clue in The Times
S
O
U
B
R
I
Q
U
E
T
More clues leading to the result SOUBRIQUET
Buddy explains!

The straight part
We know that "Handle" is the straight/definition part of the clue. The straight part is often a synonym or definition, in this case handle = soubriquet.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 SOUBRIQUET mean?
SOUBRIQUET noun- A familiar name for a person (typically a shortened version of a person’s given name).