What does the cryptic crossword clue "With top off, female working in 14 across? (7)" mean?

The wordplay uses a charade (building blocks). LIDL (synonym="LIDL") + ESS (synonym="ESS") = LIDLESS The answer is LIDLESS.

With top off, female working in 14 across? (7)

Guardian Cryptic #29371 | 28 Across | 2024-05-01 flower