Small burger (6)
I believe the answer is:
slider
'small burger' is the definition.
(I've seen this in another clue)
This is all the clue.
(Other definitions for slider that I've seen before include "Eg, fader control" , "Sir led (anag) - control mechanism" , "Control such as on a mixing desk" , "Control knob move up and down or sideways" , "American snack" .)