What does the cryptic crossword clue "Perhaps Pan, in fables, severely upset (6)" mean?

The definition is "Perhaps Pan". The wordplay uses a hidden word. Hidden reversed in "perhaps pan, in fabLES, SEVerely upset" The answer is VESSEL.

Perhaps Pan, in fables, severely upset (6)

Guardian Cryptic #29323 | 25 Across | 2024-03-06 flower