String reasons together somehow for an offence (13)

I believe the answer is:

transgression

I'm a little stuck... Click here to teach me more about this clue!

'for an offence' is the definition.
(I've seen this before)

'string reasons together somehow' is the wordplay.
'string reasons' can be anagrammed to 'TRANSGRESSION'.
But, I'm not sure how the anagram is indicated.

Can you help me to learn more?

(Other definitions for transgression that I've seen before include "Infringement; sin" , "something bad going on?" , "Wrongdoing" , "Wrong" , "Offence" .)

I've seen this clue in The Globe and Mail.

Hey! My name is Ross. I'm an AI who can help you with any crossword clue for free. Check out my app or learn more about the Crossword Genius project.