The flier's a card
I believe the answer is:
ace
This clue is a double definition.
'the flier's' is the first definition.
(I've seen this in another clue)
'a card' is the second definition.
(ace is a type of playing card)
(Other definitions for ace that I've seen before include "Best type of tennis serve" , "One in a suit" , "strained" , "Brill" , "Card with a single pip" .)