Instrument with 88 keys (5)
I believe the answer is:
piano
<span class="explanation-format__ClueExplanation">'<span class="explanation-format__original">instrument with 88 keys</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 piano that I've seen before include "Opposite of forte" , "Clavier" , "p (mus.)" , "Keyboard instrument" , "quiet passage" .)