Trombone parts (6)
I believe the answer is:
slides
'trombone parts' is the definition.
(I've seen this in another clue)
This is all the clue.
(Other definitions for slides that I've seen before include "Sloping chutes in the playground" , "Pieces of glass for study of specimens" , "Slips, slithers" , "Pieces of glass under the microscope" , "Sloping chutes in playgrounds" .)