Almost every diver wanting protection for breathing (5)
I believe the answer is:
alive
'breathing' is the definition.
(I've seen this in another clue)
I can't explain the rest of the clue.
Can you help me to learn more?
(Other definitions for alive that I've seen before include "Vital, vibrant" , "answer, as it happens" , "Aware" , "Not yet pushing up the daisies" , "Go or walk briskly" .)