What does the cryptic crossword clue "In this world, or possibly another (2,5)" mean?

The wordplay uses an anagram. anagram of ANOTHER ("another") [anagram: "world,"] = ONEARTH The answer is ONEARTH.

In this world, or possibly another (2,5)

Guardian Cryptic #25377 | 20 Down | 2011-07-18 flower