What does the cryptic crossword clue "Easily handled in vast endlessly vague domain (8)" mean?

The wordplay uses a container (one word inside another). YARE (synonym="YARE") in GREA (synonym="GREA") = GREYAREA The answer is GREYAREA.

Easily handled in vast endlessly vague domain (8)

Independent Cryptic #11470 | 21 Across | 2023-07-17 flower