Now so flustered and faint! (5)
I believe the answer is:
swoon
'faint' is the definition.
(I know that faint can be written as swoon)
'now so flustered' is the wordplay.
'flustered' is an anagram indicator.
'now'+'so'='nowso'
'nowso' anagrammed gives 'SWOON'.
'and' is the link.
(Other definitions for swoon that I've seen before include "Show ecstasy" , "Lose consciousness" , "Pass out" , "experience ecstasy" , "Fall fainting" .)