Delivering global shifts in eye treatment? (8)
I believe the answer is:
tectonic
'delivering global shifts' is the definition.
I can't judge whether this definition defines the answer.
'in eye treatment?' is the wordplay.
'in' indicates putting letters inside.
'eye' becomes 'tonic' (I am not sure about this - if you are sure you should give a lot more credence to this answer).
'treatment?' becomes 'ECT' (ECT is an example).
'tonic' placed around 'ect' is 'TECTONIC'.
Can you help me to learn more?
(Other definitions for tectonic that I've seen before include "associated with global movement" , "Relating to movements or distortion within the earth's crust" , "Relating to Earth's crust structure" , "Concerned with construction" , "Pertaining to the structure or movement of the earth's crust" .)