The Planets composer (5)
I believe the answer is:
holst
<span class="explanation-format__ClueExplanation">'<span class="explanation-format__original">the planets composer</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 holst that I've seen before include "Gustav - (The Planets)" , "Gustav --, English composer" , "British composer, 1874-1934" , "Composer of The Planets, d. 1934" , "Planets Suite composer" .)