What does the cryptic crossword clue "Infection for the oculist? Yes! (4)" mean?

The definition is "Infection". The wordplay uses a hidden word. Hidden in "infection for the oculiST? YEs!" The answer is STYE.

Infection for the oculist? Yes! (4)

Guardian Cryptic #29287 | 12 Across | 2024-01-24 flower