Male rabbit (4)
I believe the answer is:
buck
<span class="explanation-format__ClueExplanation">'<span class="explanation-format__original">male rabbit</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 buck that I've seen before include "Male beast" , "Male hare" , "type of vaulting-horse" , "some Australians try to make fast" , "young man" .)