What does the cryptic crossword clue "A hitch, with landmass quaking in Pacific territory (7,7)" mean?

The wordplay uses an anagram. anagram of A + HITCH, + LANDMASS = CHATHAMISLANDS The answer is CHATHAMISLANDS.

A hitch, with landmass quaking in Pacific territory (7,7)

Independent Cryptic #11600 | 14 Across | 2023-12-15 flower