What does the cryptic crossword clue "First appearance not top-class – a liability! (4)" mean?

The definition is "liability!". The wordplay uses a deletion. DEBT (deletion) = DEBT; definition: "– a liability!" The answer is DEBT.

First appearance not top-class – a liability! (4)

Guardian Cryptic #29481 | 15 Across | 2024-09-06 flower