Presto's opposite (5)
I believe the answer is:
lento
<span class="explanation-format__ClueExplanation">'<span class="explanation-format__original">presto's opposite</span>' is the definition.<br/ ><span class="explanation-format__explanation">(I've seen this in another clue)</span><br/ ><br/ >This is the entire clue.<br/ ></span>
(Other definitions for lento that I've seen before include "It's slower than adagio" , "Old sayings" , "Slow (music)" , "Slow (mus.)" , "Instruction to players" .)