Top cards (4)
I believe the answer is:
aces
<span class="explanation-format__ClueExplanation">'<span class="explanation-format__original">top cards</span>' is the definition.<br/ ><span class="explanation-format__explanation">(I've seen this before)</span><br/ ><br/ >This is all the clue.<br/ ></span>
(Other definitions for aces that I've seen before include "Top (or bottom) cards" , "Expert fliers" , "that are non-returnable" , "passes with flying colours in US" , "Unreturnable services" .)