Smallest bills (4)
I believe the answer is:
ones
<span class="explanation-format__ClueExplanation">'<span class="explanation-format__original">smallest bills</span>' is the definition.<br/ ><span class="explanation-format__explanation">(I've seen this in another clue)</span><br/ ><br/ >This is all the clue.<br/ ></span>
(Other definitions for ones that I've seen before include "Individuals" , "Aces" , "Singletons" , "1 & 1 & 1" , "(Of ship) returning to port of origin" .)