Sandwich served with tzatziki (4)
I believe the answer is:
gyro
'sandwich served with tzatziki' is the definition.
(I've seen this in another clue)
This is all the clue.
(Other definitions for gyro that I've seen before include "Stabilising device" , "Spin-stabilised device" , "Spinner" , "Rotating device providing stability" , "Rotating stabiliser" .)