What does the cryptic crossword clue "Lawn weed? Cut the whole lot up (8)" mean?

The definition is "L". The wordplay uses a reversal. PRUNE (synonym="”Cut”") + ALL (reversal="”the whole lot”") = PRUNELLA The answer is PRUNELLA.

Lawn weed? Cut the whole lot up (8)

Guardian Cryptic #29270 | 1 Down | 2024-01-04 flower