The objective for people in general is to stop pollution and keep alive (7)
I believe the answer is:
sustain
'keep alive' is the definition.
(I've seen this before)
I cannot understand how the rest of the clue works.
Can you help me to learn more?
(Other definitions for sustain that I've seen before include "Bear, hold, up" , "Uphold, strengthen" , "Carry" , "Strengthen; suffer" , "Provide nourishment" .)