The most common and most likely answer to this crossword clue is the 6 letter word VARLET
I've seen this crossword clue in The Guardian
V
A
R
L
E
T
More clues leading to the result VARLET
Buddy explains!

The straight part
We know that "The old rascal/The old rascal" is the straight/definition part of the clue. The straight part is often a synonym or definition, in this case the old rascal/the old rascal = varlet.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 VARLET mean?
VARLET noun- A servant or attendant.
- Specifically, a youth acting as a knight's attendant at the beginning of his training for knighthood.
- A rogue or scoundrel.
- The jack.