A slow movement (5)
I believe the answer is:
largo
I believe this clue is a double definition.
'a slow' is the first definition.
(I've seen this before)
'movement' is the second definition.
(largo is a kind of movement)
(Other definitions for largo that I've seen before include "Musical piece" , "Florida key: musical slow movement" , "Slow and dignified, like Handel's composition" , "Played with dignified slowness" , "Slow passage" .)