What does the cryptic crossword clue "Sire he's upset: she inherits the prize (7)" mean?

The wordplay uses an anagram. anagram of SIRE + HE'S = HEIRESS The answer is HEIRESS.

Sire he's upset: she inherits the prize (7)

Independent Cryptic #11807 | 20 Across | 2024-08-13 flower