What does the cryptic crossword clue "Upsetting competition for Perrier is not wise (5)" mean?

The definition is "not wise". The wordplay uses a reversal. EVIAN (reversal="rival for Perrier") = NAIVE; definition: "not wise" The answer is NAIVE.

Upsetting competition for Perrier is not wise (5)

Times Cryptic #28751 | 4 Down | 2023-11-03 flower