Pass out (5)
'pass out' is the definition.
(fainting is a kind of passing out)
This is the entire clue.
(Other definitions for faint that I've seen before include "Weak" , "Barely perceptible" , "dull" , "Hard to see" , "Swoon - pale" .)
(Other definitions for swoon that I've seen before include "Show ecstasy" , "Display of extreme emotion" , "Faint (with emotion)" , "Fall fainting" , "experience ecstasy" .)