One great fighter pilot (3)
I believe the answer is:
ace
I believe this clue is a triple definition!
'one' is the first definition.
(ace has a value of one in some card games)
'great' is the second definition.
(ace can informally mean very good)
'fighter pilot' is the third definition.
(I've seen this in another clue)
(Other definitions for ace that I've seen before include "Entertain" , "smashing" , "Top card or champion" , "winner in court" , "Good; service; card" .)