What does the cryptic crossword clue "It's a fag preparing grapes (6)" mean?

The definition is "It’s a fag". The wordplay uses an anagram. anagram of GRAPES = GASPER; definition: "It's a fag" The answer is GASPER.

It's a fag preparing grapes (6)

Guardian Cryptic #29267 | 3 Down | 2024-01-01 flower