What does the cryptic crossword clue "Barrier in dim mall that's abandoned (7)" mean?

The definition is "Barrier". The wordplay uses an anagram. anagram of DIM + MALL = MILLDAM; definition: "Barrier" The answer is MILLDAM.

Barrier in dim mall that's abandoned (7)

Independent Cryptic #11705 | 21 Across | 2024-04-16 flower