Indicates surprised comments about backing tracks (8)
I believe the answer is:
gestures
'indicates' is the definition.
The answer and definition can be both to do with communicating as well as being verbs in their -s form.
Maybe they are linked in a way I don't understand?
'surprised comments about backing tracks' is the wordplay.
'surprised comments' becomes 'gees' (I am not sure about this - if you are sure you should give a lot more credence to this answer).
'about' is an insertion indicator.
'backing' shows that the letters should be reversed in order.
'tracks' becomes 'ruts' (rut can mean a track).
'ruts' back-to-front is 'stur'.
'gees' placed around 'stur' is 'GESTURES'.
Can you help me to learn more?
(Other definitions for gestures that I've seen before include "Demonstrative motions of the hands" , "Movements to express something" , "Make signs with hand movements" , "Motions that express thoughts" , "waves" .)