What does the cryptic crossword clue "Regurgitated food next to queen finding bun filling (6)" mean?

The wordplay uses a reversal. GRUB (reversal="GRUB") + ER (synonym="ER") = BURGER The answer is BURGER.

Regurgitated food next to queen finding bun filling (6)

Independent Cryptic #11866 | 4 Down | 2024-10-21 flower