What does the cryptic crossword clue "The main challenges for sopranos, as you can hear (4,4)" mean?

The definition is "The main". The wordplay uses a homophone (sounds like). sounds like HIGH C’S (challenges for sopranos) The answer is HIGH SEAS.

The main challenges for sopranos, as you can hear (4,4)

Times Cryptic #28768 | 15 Across | 2023-11-23 flower