What does the cryptic crossword clue "Reason a trip to the tobacconist is on and off? (5,3)" mean?

The definition is "Reason a trip to the tobacconist is on and off?". The wordplay uses a double definition. Double definition The answer is SNUFFOUT.

Reason a trip to the tobacconist is on and off? (5,3)

Guardian Cryptic #29499 | 15 Down | 2024-09-27 flower