What does the cryptic crossword clue "Fossil fuel, Rishi’s confessed addiction (4)" mean?

The definition is "Fossil fuel, Rishi’s confessed addiction". The wordplay uses a double definition. Double definition The answer is COKE.

Fossil fuel, Rishi’s confessed addiction (4)

Guardian Cryptic #29426 | 9 Across | 2024-07-04 flower