What does the cryptic crossword clue "Ancient city’s the reverse of elevated and not totally pleasant (5)" mean?

The wordplay uses a reversal. PU (synonym="PU") + NIC (synonym="NIC") = PUNIC The answer is PUNIC.

Ancient city’s the reverse of elevated and not totally pleasant (5)

Guardian Cryptic #29537 | 24 Across | 2024-11-11 flower