Wild horse (5)
<span class="explanation-format__ClueExplanation">'<span class="explanation-format__original">wild horse</span>' is the definition.<br/ ><span class="explanation-format__explanation">(I've seen this before)</span><br/ ><br/ >This is the entire clue.<br/ ></span>
(Other definitions for mustang that I've seen before include "Trotter" , "creature" , "Wild horse of the West" , "Small, half-wild horse of the U.S." , "Small, wild US horse" .)
(Other definitions for brumby that I've seen before include "Wild horse in Australia" , "One Australian breaks in" , "H [HORSE]" .)