Male sibling (7)
I believe the answer is:
brother
<span class="explanation-format__ClueExplanation">'<span class="explanation-format__original">male sibling</span>' is the definition.<br/ ><span class="explanation-format__explanation">(brother is a kind of male sibling)</span><br/ ><br/ >This is all the clue.<br/ ></span>
(Other definitions for brother that I've seen before include "Union member - male relative" , "Fellow-member" , "Male sibling" , "Trade unionist" , "Relation" .)