Crossword Genius

Protective mechanism ensures triumph against dangerous opponents (4-4)

Ross

I believe the answer is:

fail-safe

I'm a little stuck... Click here to teach me more about this clue!

'protective' is the definition.
Both the answer and definition are adjectives. Maybe they are linked in a way I don't understand?

I don't understand the remainder of the clue.

Can you help me to learn more?

(Other definitions for fail-safe that I've seen before include "Device to ensure proper operation" , "Sure to succeed" , "Unlikely to go wrong" , "It ensures a return to a safety when something goes wrong with a mechanism" , "Designed to prevent accidents in the case of malfunction" .)

I've seen this clue in The Guardian.
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