Buffalo coin (6)
I believe the answer is:
nickel
<span class="explanation-format__ClueExplanation">'<span class="explanation-format__original">buffalo coin</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 nickel that I've seen before include "Silvery white metal" , "Silvery-white metal" , "not worth much in America" , "Element; five cents in US" , "A 5-cent coin in USA" .)