One fighter pilot (3)
I believe the answer is:
ace
This clue is a double definition.
'one' is the first definition.
(ace has a value of one in some card games)
'fighter pilot' is the second definition.
(an ace pilot)
(Other definitions for ace that I've seen before include "Unbeatable service" , "Top card or champion" , "first-class" , "'wicked'!" , "Brill" .)