Indifferent gesture (5)
I believe the answer is:
shrug
'indifferent gesture' is the definition.
(I've seen this before)
This is all the clue.
(Other definitions for shrug that I've seen before include "Gesture of indifference or ignorance" , "Momentarily raise the shoulders" , "Shoulder gesture" , "Gesture of resignation" , "So-what gesture" .)