What does the cryptic crossword clue "Water feature essential to partner Trevi Rome in return (10)" mean?

The wordplay uses hidden reversed. Hidden (‘feature essential to’) and reversed (‘in return’) in parTNER TREVI Rome The answer is RIVERTRENT.

Water feature essential to partner Trevi Rome in return (10)

Independent Cryptic #11961 | 11 Across | 2025-02-08 flower