The most common and most likely answer to this crossword clue is the 10 letter word TRANSGRESS
I've seen this crossword clue in The Daily Telegraph
T
R
A
N
S
G
R
E
S
S
More clues leading to the result TRANSGRESS
- Horrible stranger’s second sin
- Offend stranger playing with small son
- Strangers surprisingly committing small sin
- Fled Solicitor-General, breaking lock to commit offence
- Offend the Pole in the midst of the drunken strangers
- Horrible stranger's second sin
- Strangers getting jiggy with soprano might do this
Buddy explains!

The straight part
We know that "Offend" is the straight/definition part of the clue. The straight part is often a synonym or definition, in this case offend = transgress.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 TRANSGRESS mean?
TRANSGRESS verb- To exceed or overstep some limit or boundary.
- To act in violation of some law.
- (construed with against) To commit an offense; to sin.
- (of the sea) To spread over land along a shoreline; to inundate.