The most common and most likely answer to this crossword clue is the 4 plus 4 letter word SCOT FREE
I've seen this crossword clue in Financial Times
S
C
O
T
F
R
E
E
More clues leading to the result SCOT FREE
- Secret of criminal avoiding punishment
- Second bed delivered without damage
- Restore defectors removed without penalty!
- Strange secret of not having to pay anything
- An escapee from Barlinnie could be one suffering no harm
- Queen Mary was not unpunished
- Defectors renouncing Germany released without suffering punishment
- Secret of behaving badly and escaping punishment
- Clear of secret corruption
- …to see croft rebuilt without charge
Buddy explains!

The straight part
We know that "Queen Mary was not/unpunished" is the straight/definition part of the clue. The straight part is often a synonym or definition, in this case queen mary was not/unpunished = scot free.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 SCOT FREE mean?
SCOT FREE adverb- Free of scot, free of tax.
- Without consequences or penalties, to go free without payment.