What does the cryptic crossword clue "Lizards upsetting us again (7)" mean?

The definition is "Lizards". The wordplay uses an anagram. anagram of US + AGAIN = IGUANAS; definition: "Lizards" The answer is IGUANAS.

Lizards upsetting us again (7)

Daily Mail Cryptic #17234 | 21 Down | 2023-11-22 flower