Business leader (4)
(Other definitions for boss that I've seen before include "Person in charge - raised knob" , "Stud; employer" , "designer" , "Stud; chief" , "One managing" .)
<span class="explanation-format__ClueExplanation">'<span class="explanation-format__original">business leader</span>' is the definition.<br/ ><span class="explanation-format__explanation">(synonyms)</span><br/ ><br/ >This is all the clue.<br/ ></span>
(Other definitions for magnate that I've seen before include "Fellow with a lot of money" , "Fat cat" , "Important fellow" , "Wealthy business leader" , "Tycoon" .)