Air force heroes (4)
I believe the answer is:
aces
<span class="explanation-format__ClueExplanation">'<span class="explanation-format__original">air force heroes</span>' is the definition.<br/ ><span class="explanation-format__explanation">(I've seen this in another clue)</span><br/ ><br/ >This is the entire clue.<br/ ></span>
(Other definitions for aces that I've seen before include "Two will make deuce" , "They're high and low on cards" , "Tennis serves the receiver can't reach" , "Ones or elevens in cards" , "Experts (in their field)" .)