What does the cryptic crossword clue "Stagger out to lunch in wrong direction (4)" mean?

The definition is "Stagger". The wordplay uses a reversal. NUTS (reversal="out to lunch") = STUN; definition: "Stagger" The answer is STUN.

Stagger out to lunch in wrong direction (4)

Guardian Cryptic #29191 | 15 Across | 2023-10-03 flower