Crackerjack
<span class="explanation-format__ClueExplanation">'<span class="explanation-format__original">crackerjack</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 ace that I've seen before include "fighter pilot" , "SERVE?] that's non-returnable" , "even higher than the king" , "Possibly a diamond" , "One-spotted card" .)
<span class="explanation-format__ClueExplanation">'<span class="explanation-format__original">crackerjack</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 pro that I've seen before include "Competent person" , "With qualifications" , "Favouring the professional" , "Skilled" , "In short, not an amateur" .)