Pilot ace through until end of war (7)
I believe the answer is:
aviator
'pilot' is the definition.
(thesaurus)
'ace through until end of war' is the wordplay.
'ace' becomes 'a'.
'through' becomes 'via' (I've seen this before**).
'until' becomes 'to' (I've seen this in other clues).
'end of' says to take the final letters.
The last letter of 'war' is 'r'.
'a'+'via'+'to'+'r'='AVIATOR'
(Other definitions for aviator that I've seen before include "Flier" , "He travels up" , "Air pilot" , "Pilot of plane" , "Aircraft pilot" .)